In an apparent bid to stifle protests in West Germany over the U.S. bombing raid on Libya, Chancellor Helmut Kohl announced today that his government had acquired its own conclusive proof that the Libyan People's Bureau in East Berlin bore responsibility for the bombing 11 days ago of a West Berlin discotheque that killed two persons and wounded more than 200 others.

Kohl warned against the resurgence of "primitive anti-Americanism" and contended that the discotheque bombing "caused more injuries than were caused by the United States" in its air raid against Libyan military targets.

In contrast to Bonn's expressions of support for the Reagan administration, anti-American protest rallies have swept West Germany in the wake of the raid. Opinion polls suggest that as many as three-quarters of the voting public opposed the American action, with only 7 percent backing Kohl's stance. Last night, demonstrators in West Berlin engaged in violent clashes with police, and the windows of several American business offices were smashed.

Political turmoil and protests in the wake of the U.S. action also continued in other parts of the world today, with anti-American demonstrations in Italy, Britain, Greece, Pakistan and Sudan, where 10,000 people gathered in in Khartoum to denounce the United States. At a NATO meeting in Brussels, Spain strongly criticized the bombing raid.

In France, where criticism of the raid has been somewhat more muted than elsewhere in Europe, former president Valery Giscard d'Estaing said he approved of the U.S. attack and called it "justified."

The protests have intensified security worries at U.S. military outposts here, which have been a target of bombings in the past by West German radical groups such as the Red Army Faction.

All nonmilitary vehicles are being closely examined as they enter U.S. bases. Night curfews, from midnight to 5 a.m., have been imposed on unmarried soldiers living in barracks. The U.S. Army command also has issued directives that "strongly encouraged all soldiers to avoid bars and restaurants frequented by large groups of Americans."

Kohl's remarks today, delivered in a parliamentary debate, seemed designed to justify the characterization of the U.S. raid as "a preventive strike against the further escalation of terrorism" and to defuse a revival of anti-Reagan sentiment in West Germany.

Kohl said, "We will not allow our American friends and allies to be bombed out of our country." He noted that "the Americans felt, as they tell us again and again, that they had been left alone in the fight against international terrorism."

The Kohl government's position is understood to be that it agrees with the United States on the need for more concerted cooperation to combat international terrorism but that it believes the Reagan administration's emphasis on economic sanctions and military force is ineffective and potentially counterproductive.

The West Germans, who feel they are more experienced in dealing with terrorism and understand it better, also contend that resorting to military force risks alienating moderate Arab states from the West, encourages more terrorism by Middle East extremists and threatens to turn public opinion in Western Europe against the United States.

"It is easy to criticize the United States for resorting to measures we would not have chosen," Kohl said. "If we Europeans do not want to follow the Americans for reasons of our own, we must develop political initiatives. We will not eliminate international terrorism simply by wailing and lamenting."

In defending the Reagan administration, Kohl cited a series of Libyan-inspired attacks that have taken place in Europe that culminated recently with the West Berlin bombing. For the first time, Kohl said "clear, valid evidence" independent from U.S. intelligence had been obtained by West German experts who decoded messages sent to Tripoli from the Libyan People's Bureau in East Berlin.

West German government spokesman Friedheim Ost said today that Libya probably was involved in two other attacks in West Berlin and on West German territory in 1981 and 1983, according to Deutsche Presse-Agentur.

Kohl's revelation that West Germany had reached its own determination about the origin of the West Berlin bombing was clearly aimed at rebutting opposition charges that his government was blindly following American dictates without any persuasive clues of its own.

On Tuesday, Dieter Piete, head of a special West Berlin police unit investigating the bombing, said his forces had still not uncovered any "concrete indications" of who was behind the bombing.