Saudi Arabia, Qatar and Oman mounted an urgent diplomatic push to dissuade US President Donald Trump from launching an attack on Iran, warning that such a move could lead to “grave blowbacks in the region,” a senior Saudi official said on Thursday.

Speaking to AFP on condition of anonymity, the official said the three Gulf states led a “long, frantic, last-minute effort” to convince Trump to give Tehran an opportunity to demonstrate good intentions. “Communication is still under way to consolidate the trust gained and the current positive atmosphere,” the official added.

The intervention comes amid mounting international concern over Iran’s violent crackdown on nationwide protests. A New York Times report has estimated that more than 3,400 people have been killed and over 18,400 detained during the unrest.

Fears have also grown that Tehran could resort to executions to suppress dissent, after Iranian prosecutors indicated they would seek capital punishment under charges of “moharebeh” — or “waging war against God” — against some detainees. Trump warned on Tuesday that Washington would respond forcefully if executions were carried out. “We will take very strong action if they do such a thing,” he told CBS News.

The US president has further escalated pressure by announcing a 25% tariff on countries that continue doing business with Iran. In a post on Truth Social, he wrote: “Effective immediately, any Country doing business with the Islamic Republic of Iran will pay a Tariff of 25% on any and all business being done with the United States of America.”

Iran’s Foreign Minister Abbas Araghchi cautioned Trump “not to repeat the same mistake you made in June” in an interview with Fox News. President Masoud Pezeshkian has accused the United States and Israel of trying to destabilise Iran by fuelling unrest. While saying the government would listen to public grievances, he warned against violence and urged Iranians to distance themselves from what he called “rioters and terrorists.”