Anti-government protests have continued for a third consecutive day in a number of cities across Iran, despite officials calling on citizens to avoid "illegal gatherings".
Sparked by anger over Iran's ailing economy, the rallies have gained momentum and are described as the largest in nearly a decade.
In the capital, dozens of students on Saturday chanted anti-government slogans outside Tehran University, before being dispersed by riot police and large crowds of pro-government demonstrators.
Videos posted on Twitter by the New-York based Center for Human Rights in Iran appeared to show police in riot gear clashing with protesters outside the gates to the Tehran University. A second video showed smoke-shrouded streets, purportedly from tear gas, in the same area.
Al Jazeera could not authenticate the footage, but semi-state news agency Fars also reported confrontations between police and protesters at Tehran University.
Small crowds of protesters also rallied in Shahr-e Khord and Kermanshah, according to photos and videos posted on social media on Saturday.
The rallies appeared to take place despite Interior Minister Abdolrahman Rahmani Fazli calling on people earlier in the day not to participate in what he called "illegal gatherings".
The protests first broke out on Thursday in Masshad, Iran's second-largest city, with people taking to the streets to denounce a surge in the prices of basic foods, the sluggish economy and unemployment.
The rallies spread to Tehran and other major cities on Friday. Dozens of arrests were also reported.