Iran's semi-official Fars news agency reports that a man taking part in a protest in the northern province of Alborz was fatally shot.
The Saturday report says a protest was taking place a day earlier in Karaj, some 50 kilometers (30 miles) west of Tehran, when someone fired from a car. There were no additional details.
Fars reported authorities arrested 20 protesters and many of the protest leaders were women.
There have been several demonstrations in Iranian cities in recent days over economic conditions and public buildings have been damaged.
The Iranian rial has dropped to a record low amid growing concerns about renewed US sanctions, which kick in on Monday.
Also on Friday, about 500 protesters attacked a seminary in Karaj and broke windows with stones and bricks.