The protest lasted for just under five hours.
Around 1,500 protesters have marched through central London to call on the UK Government to close the Iranian embassy.
Demonstrators gathered outside Downing Street on Saturday afternoon before starting the journey on foot to the embassy in Westminster.
In speeches made at the start of the demonstration, organisers called on the UK Government to proscribe the Islamic Revolutionary Guard Corps (IRGC).
Some people held pictures of Iran’s exiled crown prince Reza Pahlavi, who one demonstrator said was “standing with the people of Iran”.
The woman, who did not wish to be named, added: “We support him to be our next king or alternative to this regime.”
As the protesters travelled through central London, chants of “IRGC’s terrorist, UK put them on the list” could be heard.
One participant, an Iranian national who did not want to be named, said Mr Pahlavi is the “only alternative” leader.
He added: “We are not a dictatorship, we don’t want a dictatorship, we just want a democracy.”
One demonstrator, named only as Sam, 35, said he attended the protest to “support revolution in Iran and the Iranian people who are fighting for their freedom, fighting terrorism”.
Protesters near the front of the march held a banner which read: “The people of Iran are desperate for President Trump’s help. We need military support.”
Chants of “shut down the Iranian embassy”, “deport the Iranian diplomats” and “Trump, Trump, act now, act now” were also shouted.
Romana Yasynovska, a Ukrainian national living in London, attended the protest on Saturday.
She held a sign which read “I am a Ukrainian mom. I’m here for a world where my daughter and Iran’s daughters can share the same right – to be women”.
The 44-year-old said both Ukrainian and Iranian people “just want to live in our land, raise our children, have our own tradition, choose what way of life we live”.
She added: “Today I am trying to support them because I know how important that is and every time when some foreigners come to our Ukrainian rallies, it’s priceless for us.
“Now I’m doing something for people who maybe don’t have as much support as we do.”
The protest, which was peaceful, lasted for just under five hours.
Participants were told before the demonstration to remain on a defined route stretching from near Downing Street, down Pall Mall and along Piccadilly.
The Metropolitan Police imposed conditions on Friday evening to “prevent serious disruption” and “limit disturbance” to local residents.
