JERUSALEM — In a watershed article in a leading Israeli newspaper, a top diplomat from the United Arab Emirates warned the Israeli public on Friday that unilateral annexation of West Bank territory would endanger Israel’s warming ties with Arab countries.

Writing in Friday’s Yediot Ahronot, Yousef al-Otaiba, the Emirates’ ambassador to the United States, appealed directly to Israelis in Hebrew to deter Prime Minister Benjamin Netanyahu from following through on his promise to annex occupied territory as early as next month.

“It’s Either Annexation or Normalization,” the headline over his op-ed declared.

The article rebutted an argument by Mr. Netanyahu that annexing West Bank land that the Palestinians have counted on for a state would not imperil Israel’s chances of forging deeper relations with countries like the Emirates and Saudi Arabia.

Mr. Netanyahu, echoed by a host of right-wing allies, maintains that Arab countries have too much to gain from Israel — in security, technology and commerce, among other realms — to continue sticking up for the Palestinians.

But Mr. al-Otaiba, a close adviser to Sheikh Mohammed bin Zayed, the crown prince of Abu Dhabi, said that this simply was not true.

“Annexation will definitely, and immediately, reverse all of the Israeli aspirations for improved security, economic and cultural ties with the Arab world and the United Arab Emirates,” Mr. al-Otaiba wrote in what was thought to be the first such article by an Emirati official in an Israeli newspaper.

Mr. Netanyahu has vowed to push through annexation after July 1, in connection with the Trump administration’s plan for resolving the Israeli-Palestinian conflict. But while Mr. Netanyahu and some of his allies in the Trump administration are pressing for speed, eager to act before the November presidential election in the United States, others in Washington are pumping the brakes, in part out of concern about resistance in the Arab world.

The debate over annexation comes amid a broader warming toward Israel among a number of Arab states. In recent years, Gulf countries such as Saudi Arabia and the United Arab Emirates have drifted away from the Arabs’ staunch historical support for the Palestinian cause, in part because they see Israel as a potential trade partner and ally in their regional rivalry with Iran.

That has led them to blunt their criticisms of some Israeli actions, but Arab officials have called annexation a bridge too far. Top officials from Jordan, Saudi Arabia and Egypt have also condemned the annexation plan, if not on the pages of Israeli newspapers.

King Abdullah II of Jordan warned that annexation “would lead to a massive conflict” with his country. The Saudi foreign minister, Prince Faisal bin Farhan, said this week that annexation would be “a dangerous escalation that threatens the chances of resuming the peace process to achieve security and stability in the region.”

The increasing Arab opposition comes as Mr. Netanyahu faces domestic opposition to the plan, not just from the Israeli left, which has argued that annexation will lead to deeper international isolation and will undermine Israeli democracy, but also from Israeli settler leaders who had been among annexation’s strongest proponents. They fear that the plan will allow the creation of a Palestinian state and effectively end the expansion of Israeli settlements in much of the West Bank.

The Palestinians are treating any unilateral annexation as an abrogation of Israel’s agreements under the Oslo Accords signed in the 1990s. They have renounced their commitments under the Oslo agreements and ended their security cooperation with Israel.

It is unclear whether the opposition will have any effect on Mr. Netanyahu’s calculations. He did not immediately respond to Mr. al-Otaiba’s article.

Nor has he publicly said how expansive an annexation he would pursue. Options include some combination of annexing the strategic Jordan Valley, the eastern edge of the West Bank abutting Jordan; the suburban-style settlement “blocs” adjoining Israel proper; or all Jewish settlements including outposts deep in the heart of what could become a Palestinian state under President Trump’s peace plan.

Mr. al-Otaiba rejected any annexation, no matter its scope. “By virtue of its being a unilateral and calculated course of action,” he wrote, “a declaration to annex constitutes an illegal takeover of Palestinian land.”

Shimrit Meir, an Israeli analyst of the Arab world, called Mr. al-Otaiba’s article “the most effective attempt so far to influence Israeli public opinion” on the subject of annexation.

“When someone comes to you and says, ‘Listen, we are already having great relations, even though they’re not official, and we can have closer relations, but we strongly advise you not to do X,’ and he communicates from a position of openness and cooperation, people will listen,” Ms. Meir said.

The pre-emptive Arab condemnations of the annexation plan stood in contrast to how Arab governments have reacted to other recent moves by Israel and the United States seen as benefiting the Jewish state at the expense of Palestinians and Arabs. Beyond issuing pro forma statements, Arab leaders took no action in response to Mr. Trump’s decision to recognize Jerusalem as the capital of Israel, to move the U.S. Embassy there from Tel Aviv, and to recognize Israeli sovereignty over the Golan Heights, land Israel captured from Syria in 1967.

But Arab leaders could face more pressure from their own populations to respond to any annexation of West Bank territory.

Mr. al-Otaiba tried a different approach. He said annexation would “toughen Arab views on Israel” precisely when years of quiet diplomatic efforts had opened up opportunities to enhance cultural exchanges and foster mutual understanding.

He said his country had worked to encourage citizens in both countries to “think about the positive side of more open and normalized relations,” noting the Emirates’ invitation to Israel to take part in Expo 2020, a global exhibition in Dubai that was postponed until next year because of the coronavirus; its allowing Israel to establish a diplomatic presence in Abu Dhabi under the auspices of the International Renewable Energy Agency; and the opening in Dubai of a kosher catering service to feed its expanding Jewish community.

More broadly, Mr. al-Otaiba wrote, the Emirates and Israel share overlapping interests on terrorism and “aggression” — an allusion to Iran — as well as in commerce, finance, on climate change, water and technology. And as a regional hub, he said, the Emirates offered a potential “gateway” for Israel to the Middle East.

“These are the carrots, the incentives, the positive sides for Israel,” he wrote. He added that “we would like to believe that Israel is an opportunity, not an enemy,” but a unilateral annexation would be an “unmistakable signal” that Israel sees things differently.

In a video interview with The National, an English-language newspaper in Abu Dhabi, Mr. al-Otaiba put things more bluntly.

“All the progress that you see, and exchanges and openings, could be undermined by one simple step,” he said.

On the Palestinian side, reactions to Mr. al-Otaiba’s article were mixed at best. While some officials privately acknowledged needing all the help they could get to block annexation, Mr. al-Otaiba’s choice of an Israeli newspaper to convey his message drew angry responses.

Ghassan Khatib, a former spokesman for the Palestinian Authority, accused the U.A.E. of trying to exploit every opening to forge ties with Israel, and pointed to the arrival at Ben-Gurion Airport this week of an Etihad Airlines jet loaded with medical supplies intended for the Palestinians.

“Their goal is normalization,” Mr. Khatib said. “But they’re worried about negative Arab reactions, so they use the humanitarian needs of the Palestinians, and annexation, as an excuse. But at the end of the day, it harms the Arab and Palestinian positions. And it’s unnecessary.”