DUBAI—Iran launched an attack on Bahrain early Sunday, the latest incident targeting the island kingdom amid skirmishes between Iran and the U.S. as negotiations to end the war remain at a stalemate.

It wasn’t immediately clear if there was any damage, though people around Manama said they heard blasts.

Bahrain, home to the U.S. Navy’s Fifth Fleet, didn’t respond to requests for comment. Authorities twice sounded missile-alert sirens and urged the public to take shelter.

Iran’s Islamic Revolutionary Guard Corps claimed the attack, saying it targeted radar positions at Bahrain’s Riffa Air Base with six drones. Riffa sits just south of Bahrain’s capital, Manama.

The attack on Bahrain came after Iran days earlier launched their first attack on the island in two months. Iran claimed to have targeted an American early-warning radar in the country over strikes by the U.S. on southern Iran. The U.S. military’s Central Command said it shot down two Iranian drones targeting Bahrain in that attack and that it caused no damage.

Iran repeatedly hit Bahrain during the war, now in its ninth month. President Trump, meanwhile, has focused on squeezing Tehran economically with a blockade at sea and putting pressure on Iran’s neighbors to halt trade by land.

Trump has signaled that he doesn’t want to return to major combat. Still, the U.S. and Iran have been skirmishing over control of the strategic Strait of Hormuz waterway.

U.S. forces have quietly carried out a series of strikes in recent weeks on Iranian sites including Qeshm Island, which sits along much of the strait’s hairpin turn. The island is home to a major Revolutionary Guard naval facility. The group uses the island to launch drones and missiles.

U.S. and Gulf officials have said the strikes are designed to stop Iran from attacking ships in the waterway. Trump has played down the significance of the strikes, calling them minor.

Write to Jon Gambrell at jon.gambrell@wsj.com