Bahrain's Interior Ministry announced the death in Diraz early Monday, blaming "terrorists" for the attack in a post on Twitter.
The February 14 Youth Coalition, which has claimed attacks in the past, posted a video online it said showed its masked members throwing gasoline bombs at police gathered near the home of Shiite cleric Isa Qassim.
The group is named after the date of the start of Bahrain's 2011 Arab Spring protests.
Bahrain is in the midst of a yearlong crackdown on all dissent in the Sunni-ruled island kingdom. The Shiite-majority island is home to the US Navy's 5th Fleet and an under- construction British naval base.