KUWAIT, OCT. 24 -- An explosion ripped through a Pan American World Airways sales office today, two days after pro-Iranian Shiite Moslems in Lebanon vowed to strike at U.S. and European interests worldwide with thousands of suicide bombers.

{In Moscow, the Foreign Ministry said the Soviet Union was watching "with much anxiety" almost daily reports of attacks on Kuwaiti shipping, civilian and military targets. "They are unacceptable from the standpoint of either international law or humaneness and morality . . . no matter who makes such attempts," it said.}

No one was injured in the blast at 2:15 p.m. at Gharbally Travel, which handles sales for the U.S.-based airline. It came hours after Kuwait's emir, Sheik Jaber Ahmad Sabah, presided over a full Cabinet meeting in the nearby palace.

An Iranian speedboat, meanwhile, attacked a Greek-owned tanker in the Persian Gulf and set it ablaze. The 38,000-ton Prosperventure 1 was anchored off the port of Dubai with six holes along its starboard side, witnesses said. An unexploded rocket also was found aboard the vessel, shipping executives said.

The Panamanian-flag tanker, which was carrying a volatile petroleum product from Saudi Arabia to Australia, was hit with rocket-propelled grenades and machine guns in the southern gulf before dawn. The attack started a small fire but caused no casualties, said the executives.

Iranian warships seized a Norwegian car carrier in the Strait of Hormuz and searched it for Iraqi-bound cargo.

No one immediately claimed responsibility for bombing the Pan Am office, which had closed for the afternoon. The state-controlled Kuwait News Agency quoted an Interior Ministry source as saying the blast was caused by an "explosive charge" outside the building.

It followed three Iranian missile attacks on Kuwaiti oil facilities in eight days and a U.S. attack on Iranian oil platforms.