The semi-official Fars news agency quoted judiciary spokesman Gholamhosein Mohseni Ejehi as saying there were around 400 protesters held across the country but that "some were released" yesterday and today.
Last week, an Iranian reformist lawmaker, Mahmoud Sadeghi, said some 3,700 people were arrested across the country.
The protests, which began three weeks ago, were initially sparked by anger at the weak economy and official corruption, but escalated rapidly, with some protesters calling for the overthrow of the government.
Clashes broke out at some protests, and at least 21 people were killed.
Iranian authorities say the protests have been waning in recent days.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)