Videos on social media recorded gunshots fired in the vicinity of Iranian protests that were staged after Tehran admitted bringing down a passenger plane in error.
It was not immediately possible to verify the footage posted late on Sunday and which also showed blood on the ground and images of people who appeared to be security personnel elsewhere in the area carrying rifles.
Other posts showed police in riot gear hitting protesters with batons on the street, as people nearby shouted "Don't beat them!"
However, Tehran's police chief on Monday said in a statement carried by the state broadcaster's website that police in the Iranian capital did not fire on protesters and officers have been under orders to show restraint.
"At protests, police absolutely did not shoot because the capital's police officers have been given orders to show restraint," said Hossein Rahimi, head of the Tehran police.