The BBC reports that officers charged into a crowd of about 10,000 using night-sticks. Demonstration organizers had been granted a permit for two hours but the group refused to disband at the end of that time.
The United Freedom Bloc has refused to take its handful of seats in parliament, and is urging citizens to embark on peaceful revolutions like those that swept Ukraine and Georgia, until the government agrees to a rerun of the Nov. 6 election.
International observers also said there were irregularities and fraud during the vote, which brought overwhelming victory to the ruling party of President Ilham Aliyev, the son of the country's late leader, Heydar Aliyev.
Britain and the United States, which have invested billions into Azerbaijan's oil infrastructure, have urged the government to allow the demonstrators to protest peacefully.