A steady stream of cautionary messages has been coming out of the Kremlin during the past two weeks, as the Soviets press their case during the prelude to next month's arms control talks in Geneva.

According to western diplomats here, the Soviets appear intent on claiming the "peace initiative" for themselves and building up pressure on Washington, directly and through U.S. allies, to respond with what they call "deeds" and some others would call concessions.

In meetings with a British politician, the chancellor of Austria and an American businessman and in a message Wednesday to a group of physicians opposed to nuclear arms, Soviet President Konstantin Chernenko has set the tone and put into print the new lexicon of phrases to describe the Soviet position.

Each time, he has made a point of stressing that it was the Soviets who proposed the talks, specifically "new" talks on "the entire range of interconnected" nuclear questions: strategic, medium-range and space weaponry.

And, he has said, while the Soviets are prepared to consider "radical solutions" in the search for "concrete agreements" or a "mutually acceptable understanding" on arms control, it is finally up to the Americans to take a "realistic position" that would make negotiations successful.

"They have their propaganda line working full time that this was at their initiative, that it was their idea to talk about all these things together," one diplomat said of the Soviets. "What we can expect now is that they will press the other side for concessions."

The fact that the Soviets rejected last summer a U.S. proposal for talks on the full range of nuclear issues -- made in response to a Soviet probe for negotiations on space only -- is not mentioned here. Nor have Chernenko's statements resurrected previous Soviet conditions for resuming the dialogue on offensive weapons that broke down a year ago.

Those talks collapsed after the North Atlantic Treaty Organization began to deploy medium-range weapons in Western Europe, and until now, the Soviets have said the subject was nonnegotiable unless those weapons were withdrawn.

In warning against unrealistic expectations for the January meeting between Secretary of State George P. Shultz and Foreign Minister Andrei Gromyko, diplomats caution that the Soviets' true bargaining stance will not be known until negotiations begin.

They note that the Soviets are likely to press for declaratory agreements -- on a nuclear weapons freeze, on demilitarizing space and other broad areas -- while the United States will press to define the scope of and procedure for future arms control negotiations.

"Except for agreeing to talk, there is no sign yet that the Soviets have changed their position," one western diplomat said.

Kremlin spokesman Leonid Zamyatin recently scoffed at western speculation that the Soviets had backed down from their demand for the removal of Pershing II and cruise missiles already deployed in Western Europe. He insisted in an article that the United States still bears the "responsibility for the removal of the obstacles they have themselves put up," but he did not elaborate.

Foreign ministers from the seven Warsaw Pact countries, meeting recently in East Berlin, issued a more direct appeal to NATO to freeze nuclear weapons.

The Soviets' top priority, however, both in Chernenko's statements and in press acounts, remains a halt to the spread of nuclear weapons in outer space.

"Militarization of outer space, if not securely blocked, would cancel everything that has so far been achieved in the field of arms limitation, spur the arms race in other areas and dramatically increase the danger of nuclear war," Chernenko said in his message to the International Physicians for the Prevention of Nuclear War. The Communist Party daily newspaper Pravda repeated the same message today.

Diplomats here say that the Soviets' primary goal will probably be, as it has been before, to block more sophisticated testing of U.S. antisatellite systems.

By putting the onus on the United States to produce the "deeds" needed to get serious negotiations under way, the Soviets are distancing themselves from any disappointing results.

That theme already was heard last week in Eastern Europe, where Bulgarian leader Todor Zhivkov told a newspaper that success in Geneva depended on U.S. intentions. "There is hope," he said, "but there is also the danger of disappointment."

As the talks approach, diplomats here expect the Soviets to take their case to the Western Europeans. After the Nov. 22 announcement of the Geneva meeting, Soviet diplomats delivered messages in European capitals stressing that the next step toward improved relations must come from the United States, western diplomats here said.

Britain appears to be getting particular attention. Two weeks ago Moscow warmly welcomed opposition Labor Party head Neil Kinnock and during their meeting, Chernenko offered to match Britain in dismantling nuclear arsenals if a future Labor government goes ahead with its proposal to eliminate nuclear weapons on British soil.

Politburo member Mikhail Gorbachev, now solidly in the leadership's inner circle, is expected to take similar messages to London when he visits there on Dec. 15.

Many diplomats say they believe that the Soviets had concluded months ago that their refusal to return to the negotiating table was a dead-end policy. The new overture, however, was timed for after the November elections in the United States to avoid giving President Reagan any bonus.

A slight shift in tone became perceptible in September, with meetings in Washington between Reagan and Gromyko, and Gromyko and Shultz. Since then, meetings on a diplomatic level have been given a more evenhanded mention here. Standard attacks on U.S. policy still appear regularly in the press, but the more vitriolic language has cooled.

In the past few weeks, other aspects of the U.S.-Soviet relationship have been getting attention here. The Foreign Ministry devoted a recent press briefing to U.S.-Soviet cooperation on nuclear nonproliferation. High-level officials -- including Chernenko, Gorbachev and Premier Nicolai Tikhonov -- have been available for meetings with U.S. businessmen on trade matters.

A revival of agricultural exchanges -- which stopped with the Soviet invasion of Afghanistan -- is close and, according to diplomats, negotiators have resolved most major issues on a new agreement on cultural and scientific exchanges.

Progress on many of these fronts predated the Geneva proposal, but the fact that they are now getting mentioned in the Soviet press is seen here as a sign that at least some of the edge has been taken off East-West relations.

The Soviets "are back in the game," a diplomat here said. "They withdrew from it a year ago, and now essentially they are back in it."