They were found guilty of setting an ambush for police and attacking them with Molotov cocktails during demonstrations last December 23-30 in the Shiite village of Nuidrat near the Gulf state's capital Manama.
Nine other defendants were acquitted.
Tensions have been running high in Bahrain where the opposition said a Shiite teenager died on Friday after he was knocked down by a car while being chased by police during a crackdown on protesters.
Regular protests have shaken Bahrain since it crushed a Shiite-led uprising against the ruling Sunni regime in March last year. The kingdom came under strong criticism from international rights groups over the deadly crackdown.
According to the International Federation for Human Rights, around 80 people have been killed in Bahrain since the violence began on February 14, 2011.