Clashes frequently erupt on the outskirts of Manama between security forces and protesters from Bahrain's Shiite majority demanding the ruling Sunni Khalifa family surrender its grip on all key cabinet posts in favour of an elected government.
The blast went off in the village of Daih, on the edge of Manama, the ministry said on Twitter, adding an officer and two policemen were "seriously" wounded "while police were dispersing rioters".
The ministry said in a previous tweet that security forces had dispersed a "breakaway group of thugs who diverted from a funeral route in Daih to riot".
Arab Spring-inspired protests backed by Bahrain's Shiite majority began in mid-February 2011 and were brutally crushed a month later.
The International Federation for Human Rights says at least 89 people have been killed since the uprising broke out.
Last year the authorities increased the penalties for those convicted of violence, introducing the death penalty or life sentences in cases which resulted in deaths or injuries.