Soviet President Leonid Brezhnev said today that Reagan administration efforts to gain strategic superiority are doomed to failure and that the Soviet Union will produce "a proper counterbalance" to any new weapons system developed by the United States.

In his first public appearance since returning from a seven-week stay in the Crimea, where he rested and held talks with Soviet Bloc leaders, Brezhnev said the Soviet Union repeatedly has called for an end to the development of "new, even more terrible types of weapons" and that its foreign policy is based on the search for a "reliable peace."

The Soviet leader's speech was an apparent reply to the Reagan administration's recent decision to begin full-scale production of the neutron warhead. It was his first public comment on the matter. Portions of the speech, however, also suggested that Brezhnev was addressing the administration's overall plan for expanding U.S. strategic nuclear forces rather than any particular weapons system proposed by the administration.

"I shall say with all responsibility that we shall not remain indifferent to the appearance of such weapons in the arsenals of the United States and other NATO members," Brezhnev said. "If this happens, the Soviet armed forces will be in the possession of a proper counterbalance to such weapons."

The Soviet leader made the remarks during a Kremlin luncheon honoring visiting Vietnamese Communist Party leader Le Duan.

The tone of Brezhnev's speech as distributed by Tass was conciliatory, however. He did not mention any American official by name, although he clearly sought to counter charges made by President Reagan and his top officials that the Soviet Union was engaged in an unprecedented arms buildup.

"As far as the Soviet Union is concerned," Brezhnev said, "we have never sought and we are not seeking military superiority."

He added that "we do not go nor do we intend to go" beyond securing "a reliable protection" for the Soviet Union and its allies.

He appeared to restate Moscow's readiness to enter into arms-limitation talks when he said that "what is needed is not so much fine words as real deeds and a practical readiness to take account of the rights and interests of other states."

Then, apparently rebuking senior American officials, Brezhnev said that "to talk about restraint and reciprocity and at the same time to pursue a provocative policy of challenge, including in the field of armaments, is to increase mistrust and to chip away at the foundations of peace.

"To set oneself the aim of becoming stronger than all others, to lay claim to world leadership -- all this has already taken place in recent history and the outcome of such attempts is well-known."

To a Soviet audience, this was a clear allusion to Nazi Germany.

The 74-year-old Soviet leader also made no specific mention of Reagan's decision to produce the neutron device -- an issue that has produced sharp Soviet reaction and was described here as an "extremely dangerous step" that intensified the arms race and raised the threat of a nuclear war.

The neutron warhead is seen by the Soviets as threatening the balance of conventional forces because of its ability to neutralize tank forces, which comprise the mainstay of Soviet land forces. Western experts say the weapon, an enhanced-radiation device that kills personnel without destroying armor, would effectively neutralize the current Soviet numerical advantage in tanks in Europe.

Three years ago Brezhnev asserted that the Soviet Union had developed the neutron warhead but that it would not produce it unless the United States decided to do so.

Brezhnev said he and Le Duan reached "identical" views during their discussions, which deal with long-term issues of the Soviet-Vietnamese cooperation. Brezhnev also asserted that Soviet aid to Vietnam would increase and that the cooperation "will be broadened in all fields."