The victim was with officers who were attacked with firebombs, steel rods and stones while attempting to secure roads and maintain order, the Kuwait News Agency reported.
The Interior Ministry said in an earlier statement the officer had been hit with a gasoline bomb, the Lebanese newspaper The Daily Star reported.
The death came on the second day of demonstrations in Bahrain marking the second anniversary of a Shiite-led uprising against the kingdom's Sunni rulers.
A teenager was killed Thursday by police gunfire during clashes at a village near the capital, Manama.
Protesters described the killing as "cold-blooded." Prosecutors were questioning two police officers involved in the shooting.
Opposition groups are pushing for a new round of talks with the government for political reforms. The opposition wants results of the talks to go to a referendum rather than have them submitted to the island country's ruler for approval.
At least 80 people have died in two years of violence, human rights groups report.