A protester briefly replaced the present flag of Iran at its London embassy with the former flag, flown before 1979, during a demonstration, witnesses told AFP.
A video posted to social media showed a man on the balcony of the embassy, near Hyde Park, replacing the country's current flag with the one used during the rule of the ousted Shah.
The old tricoloured flag with a lion and sun used in Iran before the Iranian revolution stayed in place for several minutes before being removed, witnesses on site told AFP.
London police, in an online post, said that after the flag incident, "additional officers are being deployed to prevent any disorder" and to protect the Iranian embassy.
They said they had arrested two people, "one for aggravated trespass and assault on an emergency worker and one for aggravated trespass," and they were seeking another individual for "trespass.”
Iran has experienced waves of protests since late December, driven by a sharp decline in the value of the Iranian rial and worsening economic conditions caused by years of harsh Western sanctions.
The demonstrations began on December 28 near Tehran’s Grand Bazaar and later spread to several cities across the country.
Iran has also experienced widespread connectivity disruptions.
Iranian authorities have not released official casualty figures.
Iranian officials have accused the United States and Israel of fomenting the unrest.
