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Iranian police on Monday denied they had fired at crowds demonstrating after the government reversed course and admitted it shot down a passenger plane.

Videos posted online Sunday showed protesters shouting anti-government slogans and moving through subway stations and sidewalks, many near Azadi Square, or freedom square, after an earlier call for people to demonstrate there. Other videos suggested similar protests were taking place in other Iranian cities.

Hossein Rahimi, head of the Tehran police, denied his forces had shot at demonstrators after video emerged online appearing to show the aftermath of a woman being shot.

"At protests, police absolutely did not shoot because the capital's police officers have been given orders to show restraint," he said in a statement carried by the state broadcaster's website.

Riot police had massed outside Tehran University and at squares and landmarks across the capital as calls circulated for demonstrations.

Protesters first gathered Saturday, angrily demanding the country’s supreme leader step down after the government admitted it had unintentionally shot down the Ukrainian passenger plane Wednesday, killing all 176 people aboard.

The incident came just hours after Iran launched ballistic missiles at Iraqi bases hosting American troops in retaliation for the U.S. killing of Gen. Qassem Soleimani, head of the Quds Force.

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Foreign Minister Mohammed Javad Zarif blamed "human error at time of crisis caused by US adventurism.”

President Donald Trump tweeted early Sunday, urging Iran’s leaders: “DO NOT KILL YOUR PROTESTERS.”

To the leaders of Iran - DO NOT KILL YOUR PROTESTERS. Thousands have already been killed or imprisoned by you, and the World is watching. More importantly, the USA is watching. Turn your internet back on and let reporters roam free! Stop the killing of your great Iranian people! — Donald J. Trump (@realDonaldTrump) January 12, 2020

The president also weighed in over the weekend with messages of support for the protesters in both English and Farsi.

Videos posted to social media showed demonstrators expressing anger at the regime’s admission and what they perceived as an initial cover-up.

Most of those who died in the tragedy were Iranians and Iranian Canadians.

Also Saturday, Iran briefly detained the British ambassador to the country in what the United Kingdom said was a violation of international law.

Prior to acknowledging its mistake Saturday, Iran denied shooting down the plane and accused the United States of “a big lie.”

U.S. intelligence officials had said earlier that evidence suggested the plane was shot down by an Iranian missile by mistake, multiple officials said.

Tehran’s admission of guilt raised further questions, such as why it did not shut down its international airport or airspace while conducting strikes against U.S. targets.

Also Sunday, four members of Iraq's military were wounded in a rocket attack targeting an air base just north of Baghdad where American trainers are present, Iraqi security officials said. No group claimed responsibility for the attack.

The attack by at least six rockets came just days after Iran fired ballistic missiles at two bases in Iraq that house U.S. forces, causing no casualties.

In the weeks before Soleimani was killed, Iran was rocked by anti-government protests that prompted swift and deadly government crackdowns.

Sparked in November by hikes in gasoline prices, the Iranian demonstrations quickly expanded to cover calls for more political freedom and other issues.

Widespread economic discontent has gripped the country since May, when Trump imposed crushing sanctions after having unilaterally withdrawn from Tehran's nuclear deal with world powers.