Top Reagan administration defense and foreign policy officials tried today to enlist European leaders for the coming propaganda battle over the "Star Wars" missile defense.

"It is completely clear to me" that the Soviets will make the president's missile defense effort their prime target at the arms talks scheduled to begin next month in Geneva, Richard R. Burt, assistant secretary of state for Europe, told allied officials at the final session of a conference of senior western defense officials.

"We don't need to make any apologies to our publics" for pursuing a missile defense under the administration's Strategic Defense Initiative, Burt said.

"We cannot play into the hands of the peace movement" by allowing this new interest in missile defense to strengthen arguments that "nuclear weapons are immoral." He called for a carefully thought out plan to explain the missile defense program.

Paul H. Nitze, a key arms control negotiator in Reagan's first term, warned that NATO allies are entering a "tricky" transition phase as they strive to add defensive weapons to the offensive ones in the nuclear arsenal. Among the strains, Nitze said, will be the temptation to deemphasize offensive weapons because the Strategic Defense Initiative is under way. This must not happen, he said.

Defense Secretary Caspar W. Weinberger, who was supposed to make the final address here but was delayed by icy flying conditions in Britain, linked the Strategic Defense Initiative to the hopes of the young. His speech was read by Richard N. Perle, assistant secretary of defense for international security policy.

"Today many young people are asking," Weinberger said, "how long can we really hope to possess these terrible weapons of destruction and still prevent their ever being used?" He contended that the present generation owes it to the next at least to explore the possibility of "finding a better way of guaranteeing peace with freedom."

Perle also made this argument by pleading with European officials here "to let our young upper professionals see if they can turn our technology into making the world safer."

He said that "philosophical divison" would result if European opposition to the missile defense plan creates the impression in the United States that "those we are asked to defend say, 'We cannot defend ourselves.' "

Former senator John Tower, whom President Reagan has designated to lead the U.S. team at arms control negotiations with the Soviets, told European officials at the conference that space has become the military high ground and that it is essential that the alliance keep the Soviets from seizing it.

Tower also said pointedly that President Reagan's missile defense "would be equally effective" against the SS20 intermediate missiles pointed at Europe as the strategic rockets aimed at the United States.

A number of European officials pressed U.S. delegates to tell them specifically how their countries could get in on the Strategic Defense Initiative research program. Geoffrey Pattie, British minister of state for industry, noting this fervent interest, told the conference that "Europeans' snouts are twitching at the prospect of being at the trough."

Perle, who has been at the forefront of Reagan administration efforts to limit the export of U.S. technology to the Soviet Bloc, outlined no specific program for allied participation in the U.S. missile defense, but he said that "I have no doubt we will find a way" to let allied countries bid on the research work.

Edward Teller, a scientist who is credited with helping persuade Reagan to pursue a missile defense, said a cooperative allied effort is vital to the success of the Strategic Defense Initiative. "At the working level," Teller said, spotlighting what looms as a potential controversy, "this means elimination of secrecy barriers between allies."

Sen. Gary Hart (D-Colo.) said he sensed "a peculiar euphoria" at the Wehrkunde (defense studies) Conference about the space weapons program even though "we don't yet know whether a majority of Americans support this effort or not."

Sen. William S. Cohen (R-Maine), a member of the Senate Armed Services Committee, predicted that in the U.S. Congress "both Republicans and Democrats will support a vigorous research and development program on the Strategic Defense Initiative."