Iranian police dispersed students chanting "radical" slogans during a Saturday gathering in Tehran to honour the 176 people killed when an airliner was mistakenly shot down, Fars news agency reported.
AFP correspondents said hundreds of students had gathered early in the evening at Amir Kabir University, in downtown Tehran, to pay respects to those killed in the air disaster.
The tribute later turned into an angry demonstration.
The students chanted slogans denouncing "liars" and demanded the resignation and prosecution of those responsible for downing the plane and allegedly covering up the accidental action.
Iran said on Saturday that the Ukraine International Airlines Boeing 737 was "unintentionally" shot down on Wednesday shortly after taking off from Tehran's main airport.
All 176 people on board died, mostly Iranians and Canadians, many of whom were students.
Fars, which is close to conservatives, said the protesting students chanted "destructive" and "radical" slogans.
The news agency said some of the students tore down posters of Qasem Soleimani, the Iranian general killed on January 3 in a US drone strike on Baghdad.
Fars published pictures of demonstrators gathered around a ring of candles during the tribute and a picture of a torn poster bearing the image of a smiling Soleimani.
It said that police "dispersed" them as they left the university and blocked streets, causing a traffic jam.
In an extremely unusual move, state television mentioned the protest, reporting that the students shouted "anti-regime" slogans.
A video purportedly of the protest circulated online Saturday evening showing police firing tear gas at protesters and a man getting up after apparently being hit in the leg by a projectile.
It was not possible to verify the location of the video, or when it was filmed.
Iran's acknowledgement on Saturday that the plane had been shot down in error came after officials had for days categorically denied Western claims that it had been struck by a missile.
The aerospace commander of Iran's Revolutionary Guards accepted full responsibility.
But Brigadier General Amirali Hajizadeh said the missile operator acted independently, shooting down the Boeing 737 after mistaking it for a "cruise missile".