Isak Avazogli, a spokesman for the National Front of Azerbaijan, one of three parties making up the Azadliq (Freedom) alliance, said more than 100 people were detained.
Activists gathered along several streets in the capital, Baku, carrying red carnations and yelling "Resign!" and "Free Elections." Reports say officers using truncheons beat them back as they tried to break through police cordons, forcing them to flee.
Fuad Mustafayev, deputy head of the National Front of Azerbaijan, urged activists to suspend the rally and called on police to stop the violence. He said party leaders and authorities are meeting to discuss the situation. Avazogli said if no agreement is reached by 5 p.m. local time, protesters will resume their demonstration.