The Soviet Union won a guarded endorsement by its six Warsaw Pact allies today for its planned response to the scheduled deployment of new U.S. nuclear missiles in Western Europe.

A joint statement issued at the end of a one-day meeting of the top officials of the seven Warsaw Pact countries endorsed Moscow's view that "the arms race is acquiring an unprecedented scope" and that the United States is developing new strategic weapons and seeking to deploy its new medium-range missiles in Europe in an effort to "attain military superiority."

It laid particular emphasis on the need for reductions in nuclear arsenals and expressed "alarm" at the lack of progress at the Soviet-U.S. arms reduction talks in Geneva.

The statement also repeated Moscow's call for an East-West nuclear weapons freeze and restated proposals advanced by a January Warsaw Pact summit meeting, including a nonaggression pact between the North Atlantic Treaty Organization and Warsaw Pact and a freeze on military spending on both sides starting in January 1984.

The statement said that "proceeding from the interest of peace and their security, the states participating in the meeting declare that they will in no case allow military superiority to be achieved over them. They resolutely favor the ensuring of the balance of forces at the lowest level. In this connection they draw attention to the proclaimed position of their supreme state bodies on this issue."

Diplomatic observers said the reference to the proclaimed position involved the Soviet statement of May 28 warning that the Soviets might deploy nuclear weapons in Eastern Europe if the West deploys 572 Pershing II and cruise missiles in five Western European countries.

The fact that there was no specific reference to the May 28 statement was interpreted by the observers as an indication that Romania and possibly Hungary had insisted on a more conciliatory stand.

The tone of the joint statement, which was distributed by the news agency Tass, was unusually moderate and positive.

The Warsaw Pact nations said that particular importance must be attached to efforts to eliminate "the danger of nuclear confrontation on the European continent." They expressed "full support" for the Soviet proposals at the Geneva talks on medium-range weapons, adding:

"The participants in the meeting consider it necessary to achieve at least such an accord that would rule out the deployment of new American missiles in Western European countries and provide for a corresponding reduction of the existing medium-range weapons systems in Europe with the aim of ensuring balance on the lowest level. The attainment of such an accord is possible if both sides, displaying mutual understanding and political will, proceed from the broad considerations of peace and security."

The meeting was attended by the Communist Party leaders, premiers and defense and foreign ministers of the Soviet Union, Poland, Czechoslovakia, Hungary, East Germany, Romania and Bulgaria.

On the eve of the summit, Soviet Defense Minister Dmitri Ustinov hinted at the main theme of the gathering by asserting in a speech that the scheduled deployment of new U.S. missiles posed "a special danger" and that it would "seriously change the military-political situation," not only in Europe but in the whole world.

Ustinov said that "it would be a crime on our part to expose" the Soviet Bloc nations "to risks" posed by "many hundreds of American medium-range nuclear missiles being deployed near the threshold of our common socialist home." He said the Soviet Union would "increase" its defensive might and take countermeasures "jointly with its friends."

The wording of tonight's communique suggested alliance backing was guarded and that some members argued for continued efforts to reach an agreement at Geneva.

Some observers here speculated, however, that this could be a tactical move by the Soviets as they continue to exert pressure on public opinion in the West in hopes of influencing western governments to abandon the deployment plans.

The summit meeting preceeds the scheduled visit here next week of West German Chancellor Helmut Kohl. In recent weeks West Germany has become the focus for Soviet pressure because that is where all 108 Pershing II missiles, the principal concern of Soviet military, are to be deployed.

Soviet sources said the text of the communique had been agreed on in advance and that the leaders of the Soviet Bloc had an opportunity today to discuss various ideas for a greater political and economic cooperation among the seven nations.