The opposition website Kaleme.com says police wielding clubs tried to disperse protesters in one location, but there were few details.
Authorities have deployed hundreds of police to the main streets of Tehran.
Opposition activists based outside the country had called for a silent march on the second anniversary of the election.
Claims of fraud in the vote triggered months of protests, which were met with a deadly crackdown. It was the most serious challenge to Iran's rulers since the 1979 Islamic Revolution.
Also today, Kaleme.com said a jailed opposition activist, Hoda Saber, died of heart failure after a week on a hunger strike.
Source: express.co.uk
