Iranian students staged a rare demonstration against President Mahmamoud Ahmadinejad on Monday, lighting a firecracker and burning the head of state's photograph as he spoke, the official Islamic Republic News Agency reported.
Ahmadinejad tolerated the students, who called him a dictator, the agency reported.
"We have resisted dictatorship for many years - from before the 1979 Islamic Revolution - and nobody can bring back a dictatorship even in the name of freedom," the agency quoted the president as telling the students at Amir Kabir Technical University in Tehran.
The disturbances began when a group of students started chanting "Death to the dictator!" during the president's speech in a hall at the university.
Next the students held up a picture of the president, upside down, and set it alight, the agency reported. Finally, the students set off a firecracker.
Ahmadinejad kept his cool and finished his speech, the agency said.
There was no report of the authorities arresting any of the protesters.
The president has not always tolerated criticism. A few months ago his government banned a newspaper that had depicted him as a donkey in a cartoon.
Ahmadinejad's son used to study at Amir Kabir university.