Iran deployed scores of policemen to disperse a brief protest in downtown Tehran over a bus crash last week that killed 10 people, including eight students.
Monday's rally — which saw about 200 protesters gather — was the third consecutive day of demonstrations over the accident. Earlier protests took place inside the Azad University campus in northern Tehran.
Protesters demand the dean and other university officials resign.
Authorities have promised to investigate the crash, which took place inside campus grounds. Five people were reportedly arrested.
Iran sees a high death toll — about 17,000 killed every year — in traffic accidents. The high toll is blamed on disregard of safety measures and outdated cars.