Demonstrators, who included women, shouted "Free the prisoners!" and held up photos of people being held.
The protests in Shiite villages near the capital Manama were in response to a call from the radical February 14 Revolution Youth Commission.
Shiites, inspired by the Arab Spring in 2011, have been pushing to be given a greater say in the small country’s affairs.
The kingdom was rocked by a month-long uprising, which was crushed with the help of Gulf troops led by neighbouring Saudi Arabia, but protests continue and frequently turn violent.
