MANAMA, Bahrain (AP) _ Iraq said its jet fighters raided a large ship off Iran's coast today, a day after an Iranian gunboat rocketed a Kuwaiti freighter in the Persian Gulf.

The Iraqi state radio, monitored in Bahrain, said the warplanes ''scored an accurate and effective hit on a large maritime target,'' an Iraqi military term for a large vessel, often an oil tanker.

Gulf-based marine salvage executives said no independent confirmation of the Iraqi attack claim was immediately available, and there was no information on the ship's name or nationality.

The Iraqi radio, citing a military spokesman in Baghdad, said the jets struck at 10:35 a.m. off the Iranian coast, but did not give the precise location of the attack.

The Iraqis usually attack ships near Iran's Kharg Island oil terminal, within a 70-mile-radius military exclusion zone in the northeastern gulf.

The Iranians recently have followed a pattern of retaliating two to four days after every Iraqi attack by hitting a ship in the central sector of the gulf.

On Tuesday, Iranian gunboats attacked the 32,534-ton Kuwaiti cargo ship Al- Mirkab about 150 miles south of Kuwait, near where Iranian gunboats hit two Scandinavian supertankers with missiles on Saturday.

The Norwegian-owned Mia Margrethe, the Swedish-operated Stena Concordia and the Al-Mirkab are now anchored off Bahrain for damage assessment.

The Mia Margrethe was sailing from Kuwait with a cargo of oil and the Stena Concordia was heading for Kuwait when they were attacked. One Norwegian sailor suffered serious burns and the giant tankers had to be towed to Bahrain.

Iran has been singling out Kuwait-related vessels for its attacks in the gulf. It charges the tiny gulf state with aiding Iraq in the nearly 7-year-old Iran-Iraq war.

Iran acts against Iraq-destined cargo sailing through the Strait of Hormuz, the southern gateway to the gulf, seeking to prevent war materiel from reaching its enemy.

Iraq attacks ships sailing to or from Iran, trying to choke Iran's oil exports. Iran retaliates by hitting tankers related to Iraq or other gulf countries.

Iraq attacked the Liberian-registered oil tanker Tenacity on as it headed for Iran June 20. The raid ended a 32-day lull in the so-called ''tanker war'' that followed the May 17 Iraqi missile attack which killed 37 Americans on the U.S. Navy frigate Stark.

Iraq said its pilot mistook the Stark for an Iranian warship.

Despite the Iraqi attack, the United States considers Iran the greater threat to gulf shipping. The Reagan administration wants to put Kuwaiti tankers under the U.S. flag to protect them against Iran.

The Democratic-controlled House will vote July 9 on a proposal to request a 90-day delay in the White House plan to have U.S. ships protect Kuwaiti tankers.