The man who removed a flag from the embassy’s roof was arrested on suspicion of criminal damage, trespass on diplomatic property and assaulting police, the Metropolitan Police said.
It added “a number” of people had also been arrested on suspicion of violent disorder and a section 35 dispersal order had been imposed outside the embassy “as a result of ongoing disorder”.
“A significant police presence remains in place, including additional officers who have been deployed during the evening to prevent further disorder.”
A London Ambulance Service spokesperson said it was called at 20:45 GMT “to reports of an incident at the junction of Exhibition Road and Kensington Road”.
Four people had been taken to hospital while two others were treated at the scene, it said.
Earlier this week the Iranian ambassador in London was summoned to the Foreign Office after the killings of protesters in Iran.
Last Saturday, two people were arrested at a protest outside the embassy where a protester also climbed onto the building’s balcony and appeared to tear down the Iranian flag.