Five arrests have been made so far in which a number of officers have been injured and missiles were thrown by the crowd.
A police officer with a bloody cut on his nose was seen giving orders to fellow officers as they tried to hold back the crowd at Princes Gate at 5 p.m. on Sunday.
His injuries are not considered serious, while one video shows an angry protester being hoisted to the ground after breaking through police lines to get to the embassy.
A Met spokesperson said: “A police operation has been conducted for ongoing demonstrations near the Iranian embassy in Princes Gate, SW7.
“In the afternoon of Sunday, September 25, a large number of protesters gathered at the site, with a substantial group bent on causing a nuisance.
“More police resources were deployed to support the people on the ground after protesters tried to breach police lines and threw rockets at officers. Five arrests have been made for crimes, including violent disturbances.
“We are aware of a number of police officers who have suffered injuries while dealing with the condition; none of them are thought to be seriously injured.
“There will be a significant police presence in and around the area to monitor the situation.”
The protests came after more than a week of anti-government demonstrations in Iran following the death of Mahsa Amini – a young woman who died in police custody.
President Ebrahim Raisi pledged to “deal decisively” with the protests, which have now spread to most of Iran’s 31 provinces.
Officials say about 35 people have been killed since protests broke out against the death of Mahsa Amini in police custody.
Women have played a prominent role in the street protests, challenging and waving the country’s Islamic dress code and burning their veils.