There are reports that thousands of protesters fought with riot police in Tehran on Sunday.
Iran has ordered journalists working for international news organizations to stay indoors and not talk to citizens.
But phone calls from witnesses, videos on Youtube, and official statements on Iranian media indicate police used tear gas to break up a crowd of 3,000 protesters near Tehran's Ghoba Mosque.
The protest happened as several staff members at the British Embassy were arrested.
Meanwhile in Montreal, several hundred demonstrators peacefully walked through the downtown core to bring attention to the struggle for democracy going on overseas.
Many of the protesters support presidential candidate Mir Hossein Mossavi, and they want a full recount of the June 12 election.
At the same time, even though they live in Montreal, they do not wish to be identified for fear relatives living in Iran will be persecuted.
"We are here to show that it is not our wish that [Mahmoud] Ahmadinejad be our president," said one demonstrator.
Another added "we are mourning our young ones who are dying there in Iran."
But a second group, that walked separately along the same route, is calling for a revolution.
They demand an end to Ayatollah Ali Khamenei's role as supreme leader of the Islamic state, and the start of western-style democracy with a separation between church and state.
with files from The Associated Press
