The United States suspects a Libyan hand in the Saturday bombing of a West Berlin discotheque in which a U.S. soldier was killed and 64 other Americans were injured, but will "not necessarily" retaliate militarily, a top State Department official said yesterday.

At the same time, Robert B. Oakley, director of the State Department's office of counterterrorism, prodded U.S. allies in Europe to cooperate in efforts to blunt Libyan-inspired terrorism. He cited appeasement of Hitler in the 1930s to describe the dangers of failure to unite against Libyan leader Muammar Qaddafi, who has pledged to target American installations for terrorist attack.

"We take seriously what Qaddafi says, even though he's a madman in some respects," Oakley said on CBS News' "Face the Nation." "Hitler was also a madman in some respects, and there was a lot of trouble when people didn't take seriously what he was saying."

Oakley said the bombing of the West Berlin discotheque, popular among U.S. military personnel, fits "the pattern" of Qaddafi-sponsored terrorism. But he said the U.S. government lacks "conclusive evidence" of Libyan involvement in the early-morning attack in which 204 people were injured, including U.S. soldiers and their families. A Turkish woman also was killed.

Nor is there evidence linking the discotheque assault to last week's bombing of a TWA jetliner that killed four Americans, Oakley said.

"But you can't quite tell who bombers of this sort may be working for," he said. "Some of these terrorist organizations . . . take their directions and their money from whomever will pay them."

Oakley said there is still no certainty that the prime suspect in the bombing of TWA Flight 840, a Lebananese woman, May Elias Mansur, actually planted the explosive device under a seat "because those bombs sometimes travel for days without exploding." Mansur has denied involvement.

Three separate groups, representing West German leftist terrorists, radical Arabs and Western Europe's Red Army Faction, have said in different telephone calls to news organizations in Europe that they carried out the West Berlin bombing. None are known to have Libyan connections.

Oakley said U.S. officials nevertheless harbor "some suspicions" of a Libyan role, noting that there have been "a number of surveillances" of American embassies by Libyan agents since Qaddafi threatened to unleash terrorists.

Asked if the United States is planning military retaliation against Libya, Oakley replied, "Not necessarily. The Reagan administration looks at the use of military force in a judicious fashion on a case-by-case basis, and one of the things we have to take into account is our desire to generate as much collective action and pressure as possible."

Noting that some U.S. critics call President Reagan's antiterrorist campaign "an American obsession," Oakley cited statistics showing that only 23 of the 928 people killed by terrorism last year were American.

Qaddafi's suspected orchestration of the West Berlin bombing and last December's bloody airport attacks in Vienna and Rome in which five Americans died show that "Libyans are pushing terrorism up into Western Europe and taking a much more aggressive terrorist act which is damaging to Americans and European interests," he said.

"It's not the United States versus Libya," he said. "Think of the effect this is having upon the Europeans. We're in this together and our objective is to get the Europeans to work with us to do more about this threat, whether it be from Libya, or Syria, or Iran, or elsewhere."

Oakley said Reagan's antiterrorist campaign has failed because "international cooperation has not been great enough."

Most U.S. allies in Europe have been reluctant to join Reagan's economic sanctions against Libya, and some have been apprehensive about the escalating U.S.-Libyan military confrontation highlighted by last month's clash in the Gulf of Sidra.

Informed U.S. sources said Saturday that the administration is asking European governments to expel Libyan diplomats and agents in response to the attack in West Berlin.