Col. Muammar Qaddafi, the Libyan leader, shows increasing signs that he fears U.S. economic or military moves against his rule and is seeking to tone down his image as an international maverick, according to diplomatic sources here.

The assessments, based on Qaddafi's public statements and conversations with other Libyan officials, do not mean the Libyan revolutionary's hostility toward U.S. policy has diminished, but rather that he feels threatened by Washington's hard-line attitude, the sources say.

Referring to the pullout of U.S. citizens working in Libya in retaliation for an alleged plot to assassinate American political leaders, a European with frequent access to Libyan officials said Tripoli is "terribly preoccupied that this may be a step in a mounting line by the United States of economic sanctions and maybe even military action. Fear of the United States has been the overriding factor here for the last several months."

Several low-level government officials, apparently reflecting the fears, questioned a visiting American correspondent about the possibility of a U.S. economic boycott and the whereabouts of the U.S. 6th Fleet in the Mediterranean.

"What could the United States gain from an attack?" asked one. "It would be like a big man with tatoos on his arm beating up on a child."

The questions flow in part from a steady barrage of propaganda in the official Libyan press and television depicting the United States as a powerful enemy bent on putting down an Arab world whose cause Qaddafi defends despite defections from such "pigs of the [Persian] Gulf" as Saudi Arabia. During a recent television editorial lambasting the United States, for example, a film excerpt was screened showing President Reagan in an old cowboy role -- roundly beating his adversary in a classic western fistfight.

The day after the Reagan administration announced suspension of a strategic cooperation agreement with Israel because of Israeli annexation of Syria's Golan Heights, the main headline in the official Libyan newspaper New Dawn read: "The American Administration Announces Its Support of the Zionist Decision to Annex Golan."

More concretely, the diplomats say, the questions reflect doubts inspired by the shooting down of two Libyan SU22 jets by American F14s last August during U.S. maneuvers in the Gulf of Sidra claimed by Tripoli as Libyan territorial waters. Radio news reports that Washington may be planning more such maneuvers next month were treated with apparent concern by low-level officials escorting a group of foreign journalists here last week.

The apparent Libyan propaganda offensive also is directed at the United States. The Libyan Mission to the United Nations recently placed advertisements in American newspapers categorically denying charges that Libya planned attacks against U.S. officials and assuring that Americans working in Libya were in no danger.

[Citing "irrational misconceptions" in the United States about Libyan aims, the mission also sent letters to several U.S. journalists inviting them to an "objective political dialogue with the leader of the great 1st of September revolution to elucidate some of the political viewpoints and the ideological course of this glorious revolution."]

The diplomatic informants in Tripoli also say Qaddafi and his lieutenants have begun to fear isolation from the Western Europeans with whom Libya maintains active and vital economic relations. It is against this background, they explain, that Qaddafi responded swiftly last month to Chadian President Goukouni Oueddei's request that Libyan troops leave neighboring Chad, and that Libya has assured European governments that it no longer will combat opponents on its soil with assassination teams.

Apparently on the basis of these conciliatory moves, France declared last week that Qaddafi no longer is seeking to destabilize other countries and pledged to improve relations with Libya strained to the breaking point by the burning of the French Embassy here in February 1980.

"They also would like to have better relations with the United States," a European ambassador said. "But they just don't know how."

The momentum of Qaddafi's policies would seem to make any such peace-making difficult. Soviet advisers, estimated to number about 3,000, are present throughout the Libyan armed forces, including the general staff headquarters next to Qaddafi's offices.

"This means they are in a position to exercise considerable influence in military matters," a knowledgeable source said.

In addition, he said, Bulgarian, Czech and North Korean experts are deeply involved in maintaining Qaddafi's predominantly Soviet-supplied Air Force, and East Germans coordinate his internal security apparatus.

Aside from whatever leverage Moscow gains from this role, Qaddafi also has irritated Washington by hiring former Green Berets and Central Intelligence Agency employes to train Libyans and maintain equipment. Among them is Edwin P. Wilson, who is under indictment in the United States for conspiracy to supply arms to Libya and train terrorists there. Wilson lives in a comfortable villa in Tripoli's beachside Andalus district.