"A large group of people and security forces clashed in the Pol-e Choubi area while people were marching," Jaras website said.
The report could not be independently confirmed, as foreign media have been banned from reporting directly on protests.
The same website earlier reported that hundreds of riot police were deployed in central Tehran.
The reported incident occurred as people around Iran marked the day of Tasoua with religious ceremonies which peak on Sunday, when Shi'ite Muslims commemorate the 7th century death of Imam Hossein in a battle that sealed the schism between Shi'ite and Sunni Muslims.
Hossein was a grandson of the Prophet Mohammad.
Tension has been mounting in Iran after last Saturday night's death of leading dissident cleric Grand Ayatollah Hossein Ali Montazeri, a fierce critic of the clerical establishment who called the disputed June election fraudulent.
(Writing by Fredrik Dahl; Editing by Richard Williams)
