Iranians held mass protests on Friday across the Islamic Republic, angered by Saudi Arabia’s execution of a Shiite cleric that has enflamed regional tensions between the Mideast rivals.

Later in the day, the Iranian foreign minister insisted in a letter to the U.N. chief that Tehran has no desire to escalate tensions and said Saudis must make a “crucial choice” — either continue supporting extremists and promoting sectarian hatred or promote good neighborliness and regional stability.

The crisis has seen Saudi Arabia sever ties with Iran after crowds of protesters in Iran attacked two of its diplomatic posts on Sunday. Those assaults came after Saudi Arabia executed Sheikh Nimr al-Nimr, a prominent opposition Shiite cleric, the day before.

After Friday prayers in Tehran, thousands of worshippers joined the rally, carrying pictures of al-Nimr and chanting “Death to Al Saud,” referencing the kingdom’s royal family. They also chanted “Down with the U.S.” and “Death to Israel,” traditional Iranian slogans at protests.

The rally in Tehran lasted some 40 minutes and took place in an outdoor space at the Mosalla Mosque, the main site for Friday prayers in Tehran.

Iranian state media reported similar protests taking place in other Iranian cities and towns. Shiites across the greater Mideast have rallied throughout the week over al-Nimr’s execution.

Iranian Foreign Minister Javad Zarif said in a letter to U.N. Secretary-General Ban Ki-moon obtained Friday by The Associated Press that Iran has “no desire or interest in escalation of tension in our neighborhood” and hopes Saudi Arabia will “heed the cause of reason.”

Zarif said that from the first days of President Hassan Rouhani’s election, both he and the president have sent public and private signals to Saudi Arabia “about our readiness to engage in dialogue and accommodation to promote regional stability and combat destabilizing extremist violence.”

But he also accused the Saudis of trying to prevent or defeat the nuclear deal reached in July, of producing or mis-educating many “extremist perpetrators of acts of terror,” of supporting “extremist terrorists in Syria and elsewhere,” and waging a “senseless war” in Yemen.

Zarif also accused Saudi authorities of engaging in “numerous direct and at times lethal provocations against Iran.” He cited Saudi bombers hitting Iranian diplomatic facilities in Yemen several times, including on April 24 and Sept. 18 last year and Jan. 7, “killing two local service personnel, injuring a number of Yemeni guards and inflicting damage to the buildings.” He did not specify where the killings, injuries and damage took place.

Zarif also accused the Saudis of persistently mistreating Iraqi pilgrims, “fueling public outrage in Iran.”

On Thursday, Iran claimed that a Saudi-led airstrike the previous night had hit the Iranian Embassy in Sanaa, citing Iran’s Foreign Ministry. However, an Associated Press reporter who reached the site just after the announcement saw no damage to the building, which sits in a neighborhood near a presidential palace that’s seen many previous strikes.

Iran vowed to file a report about their claim to the United Nations, while the Saudi military issued a statement through the kingdom’s state news agency, dismissing the allegation as false.

In eastern Saudi Arabia, the home of al-Nimr and much of the kingdom’s roughly 10 to 15 percent Shiite population, Shiites held a memorial service for the cleric Thursday night. It wasn’t a funeral, as the sheikh’s brother has said Saudi authorities had already buried his body in an undisclosed cemetery.

The service ended peacefully, despite gunfire echoing in the night in the region over the last week. On Friday, the state-run Saudi Press Agency said that a man complained of being kidnapped at gunpoint by a gang and beaten in eastern Saudi Arabia. It quoted police as saying an investigation was ongoing.

A protest Friday in Bahrain saw hundreds of the country’s majority Shiites marching to denounce Saudi Arabia for al-Nimr’s execution.

The protesters in the town of Sitra, south of the Bahraini capital of Manama, chanted slogans against the government, which is allied with Saudi Arabia’s Sunni monarchy. They also carried posters of al-Nimr.

The demonstration descended into violence with police firing tear gas and birdshot while protesters threw Molotov cocktails as they tried to reach a main highway. No further details were immediately available.

The Sunni-ruled Bahrain, which sided with Saudi Arabia in the kingdom’s spat with Iran, has cut diplomatic ties with Tehran.

(AP)