Videos circulating on social media on January 12 showed protesters gathering outside Beheshti University in Tehran, chanting "the students are vigilant and are fed up with that Ali" -- a disrespectful reference to Supreme Leader Ayatollah Ali Khamenei.

The new protests came one day after Iran's military said that Ukraine International Airlines Flight PS752 was hit with two missiles fired in error by an Iranian air-defense unit manned by the Islamic Revolutionary Guards Corps (IRGC).

The crash occurred early January 8, just hours after Iran fired ballistic missiles at U.S. forces on Iraqi bases.

Demonstrators have called for those responsible for the missile strike to be tried.

Another video showed several dozen students protesting outside the Isfahan University of Technology, south of Tehran, specifically criticizing the IRGC.

"The guards are committing crimes and the leader supports them," they chanted.

The videos, and the reported protests, could not be immediately verified.

More demonstrations were reportedly scheduled for later on January 12, a day after similar events took place in at least five cities, including Tehran.

Britain's ambassador, meanwhile, said he was detained briefly by Iranian authorities as he attended a January 11 vigil for the victims of the crash.

In a post on Twitter, Rob Macaire said he attended the event in Tehran to pay respects to the victims, and was not attending any political demonstration.

Britain's Foreign Ministry called Macaire's detention a violation of international law. But Iran's Foreign Ministry summoned Macaire on January 12 to complain about what it called "his unconventional behavior of attending an illegal rally."

"Today, Rob Macaire was summoned because of his unconventional behavior of attending an illegal rally on Saturday," the report said.

At one of the January 11 demonstrations, the semiofficial Fars news agency said, some protesters ripped up photographs of Major General Qasem Soleimani, the powerful military commander who was assassinated by a U.S. drone strike on January 3 near Baghdad's airport.

Iran's military said the Ukrainian jet was shot down when it was mistaken for a "hostile target" after it turned toward a "sensitive military center" of the IRGC.

The jet's downing, the missile attack, and the killing of Soleimani have further stoked already high tensions, particularly between Tehran and Washington.

Late on January 11, U.S. President Donald Trump appealed to Iranians, expressing support for "brave" protesters and warning the Iranian government.

"To the brave, long-suffering people of Iran: I've stood with you since the beginning of my Presidency, and my Administration will continue to stand with you. We are following your protests closely, and are inspired by your courage," he wrote on Twitter on January 11 in English and Perrsian.

He added that Tehran "must allow human rights groups to monitor and report facts from the ground on the ongoing protests by the Iranian people."

"There cannot be another massacre of peaceful protesters, nor an internet shutdown. The world is watching," he added, referring to a previous round of anti-government protests in November and December that saw more than 300 people killed and a shutdown of the Internet.

Although saying its forces shot down the plane, Iran tried put some of the blame on the United States. Foreign Minister Mohammad Javad Zarif said the incident occurred "at a time of crisis caused by U.S. adventurism."

"A sad day. Preliminary conclusions of internal investigation by Armed Forces: Human error at time of crisis caused by U.S. adventurism led to disaster," Zarif wrote on Twitter.

Amirali Hajizadeh, head of the aerospace division of the IRGC, said that his unit accepted "full responsibility" for the tragedy.

Until the admission, Tehran had vehemently denied allegations by Western leaders and experts, and evidence that indicated an Iranian missile had brought down the plane.

The Ukraine International Airlines flight was en route to Kyiv, carrying 82 Iranians, 57 Canadians, 11 Ukrainians, 10 Swedes, 10 Afghans, three Germans, and three Britons.

Ukrainian President Volodymyr Zelenskiy said his country expected a full probe and compensation from Iran.

"We expect from Iran assurances of their readiness for a full and open investigation, bringing those responsible to justice, the return of the bodies of the dead, the payment of compensation, official apologies through diplomatic channels," Zelensky said on January 11.

Zelenskiy spoke later in the day by phone with Iranian President Hassan Rohani. Zelenskiy’s office said Rohani apologized for the tragedy and promised that those responsible would be held accountable. The two also discussed Iranian compensation to the victims, the office said.

With reporting by RFE/RL's Radio Farda