The Bahraini regime says it had arrested 29 people in several villages, the day before the third anniversary of mass protests which could spark more anti-regime rallies.
The Interior Ministry on Thursday threatened that it would take action against calls to hold rallies and marches and had stepped up police patrols.
Bahrain’s main opposition group Al-Wefaq has called for demonstrations to mark the anniversary.
The regime has been shaken by frequent demonstrations and clashes since demonstrators took to the streets in February 2011 to call for greater democracy.
The Persian Gulf Arab island is a US ally which has long provided a base for the US Navy’s Fifth Fleet.
Stalled reconciliation talks between the ruling family and the opposition were recently revived after the intervention of Crown Prince Salman bin Hamad Al Khalifa, seen as a relative moderate in the royal family.
But mistrust between the opposition and the Saudi-backed Al Khalifa family remains high three years after the authorities subdued the first wave of protests.
Demonstrators still frequently clash with police in Bahrain.
According to local sources, scores of people have been killed and hundreds arrested