Hundreds of Iranians were protesting outside the French Embassy in Teheran against a tentative agreement to remove an exiled Iranian opposition group from the EU's terrorist list.
A final decision on the status of the People's Mujahedeen Organization of Iran is up to EU foreign ministers, who meet Monday.
During Sunday's protest, the demonstrators chanted "Death to hypocrites" - a reference to the group.
The group was founded in Iran in the 1960s and helped followers of Ayatollah Ruhollah Khomeini overthrow US-backed shah in 1979. But it fell out with Khomeini, and thousands were killed, imprisoned or forced into exile.