Witnesses say Iranian security forces have clashed with opposition protesters in one part of Tehran.
The witnesses say authorities used batons to try to disperse demonstrators holding anti-government marches in a central square in the capital. The opposition protests were called to coincide with state-sanctioned rallies on Wednesday marking the 30th anniversary of the takeover of the U.S. Embassy.
The witnesses had no immediate reports of serious injuries or arrests among the protesters. They spoke on condition of anonymity because of fear of arrest.
Outside the former U.S. Embassy, thousands of people gathered for the annual anti-American demonstrations.