In London, protesters gathered in front of the Iranian embassy and then held demonstrations outside the Prime Minister's office at 10 Downing Street.
"We want a revolution, we want to see regime change," protester Afsi told AFP news agency.
Around 2,000 protesters gathered in Paris to criticize the regime in Tehran. Several of the demonstrators carried the Iranian flag used under the Shah before he was overthrown.
Police in Paris did not allow protesters to approach the Iranian embassy.
Protests against the Iranian regime were also held in Istanbul, Turkey.
"It's been 72 hours since we received any news from the country or from our families. No internet and no TV - we can no longer reach Iran," said Iranian Nina, who lives in Turkey.
