Five people died on the holy day of Ashura, the Iranian Ilna news agency reported.
Demonstrators threw heavy objects at police and wounded police officers, as well as Tehran Police Commander Azizollah Rajabzadeh, Tehran Police department reported.
Opposition supporters and police clashed on Ashura in Tehran. According to international news agencies, the riots resulted in the deaths of 15 people. Police arrested 300 people.
According to the Fars news agency, the nephew of Iranian opposition leader Mir-Hossein Mousavi was murdered during the clashes.