Libyan leader Col. Muammar Qaddafi was quoted last night as saying he is trying to persuade Iran to release the hostages held at the U.S. Embassy in Tehran because he fears the threat of World War III.

In an interview with journalist Oriana Fallaci to be published in Sunday's editions of the Milan daily Corriere Della Sera, the Moslem leader said:

"I have bad news. There is movement in the American military bases in Europe. The Americans are preparing parachutists and arming with armored vehicles, missles, gas, neutron bombs and other material.

"It is a serious thing, if this is really the beginning of the third world war, we must use all our force to prevent a precipitation," Qaddafi said.

Fallaci, who has interviewed Iran's religious leader Ayatollah Ruhollah Khomeini, quoted Qaddafi as saying he was personally opposed to kidnaping, particularly of individuals belonging to diplomatic missions.

Meanwhile, Arab and Iranian protesters demonstrated peacefully yesterday near U.S. diplomatic missions and other American buildings in New Delhi and London amid heavy police security.

In Bangkok, Thai police found an antitank rocket-launcher across the street from U.S. Embassy, where two explosions, apparently caused by grenades, occurred Friday night.

And in Nairobi, President Daniel arap Moi called on all churches and religious bodies in Kenya to remember the Tehran embassy hostages, who have been held captive by militant Moslems since Nov. 4.

More than 200 Iranian students participated in the New Delhi demonstration, during which the American flag was burned outside the U.S. Embassy and an effigy of President Carter outside the American Center. The students shouted anti-American slogans and dispersed peacefully after about 45 minutes.

In the southern Indian city of Madras, about 400 Iranian students were prevented by police from marching to the U.S. Consulate.

More than 1,000 London policemen protected the American Embassy there from a smaller number of Palestinian demonstrators, who staged a protest march a few blocks away.

The demonstrators, organized by Palestine Liberation Organization supporters, mingled anti-Israel and pro-Palestinian slogans with anti-American and pro-Iranian sentiments in their speeches, chants and banners.

Police prevented the Palestinians, who frequently demonstrate in London, from getting closer than about three blocks from the embassy, which has been closely guarded since the Tehran takeover.

In the Thai capital, police were trying to trace the owner of the loaded M72 launcher that was found abandoned on a building site about 45 yards across the road from the embassy entrance.

No one was injured and damaged was slight in the two explosions.

Police, who have increased security around all embassies and senior diplomats following the blasts, said they have collected more than 70 pieces of what they believe was shrapnel from M79 grenades.

No one has claimed responsibility for the incident.