Clear signs of changing Kremlin attitudes toward President Reagan and the forthcoming Soviet-U.S. talks in Geneva surfaced today as Moscow grudgingly welcomed his recent speech on control of nuclear weapons.

The Soviets initially dismissed the Reagan speech as a ploy to obscure an American quest for strategic superiority, but an apparently delayed assessment in an influential Moscow weekly newspaper today cast portions of the Reagan remarks in a positive light.

The Literary Gazette restated previous Soviet charges. "But," wire service dispatches quoted the paper as saying, "this is not the main point. The most important thing is that Mr. Reagan has spoken about peace and about negotiations, including talks about reducing arms in Europe."

The shift in the public Soviet assessment of the U.S. negotiating posture came on the last day of President Leonid Brezhnev's visit to West Germany. The trip itself was the culmination of a long Soviet effort to seek Western public support against the planned deployment of new, medium-range U.S. nuclear missiles in Western Europe.

The Literary Gazette assessment was echoed in similar, more cautious remarks by a senior Soviet politician. Both underscored the change in Soviet rhetoric and attempts to create a "positive climate" prior to the opening next Monday in Geneva of Soviet-American talks on reducing nuclear arms in Europe.

Boris Ponomaryov, an alternate member of the Politburo, was quoted by the Czechoslovak news agency as saying that Reagan's speech was "different" from previous "warlike statements heard in Washington." He rejected the substance of Reagan's proposals, however, saying that they "ignored the principles of equality and equal security."

Ponomaryov was addressing a meeting of representatives of 87 Communist parties in Prague.

The Soviets have used the Brezhnev visit to state their public position at the forthcoming Geneva talks while also making a forceful bid to portray U.S. nuclear policies as the "gravest threat" to the continent.

While pressing the campaign for European public support, Brezhnev also appears to have scored a major diplomatic victory by inducing Chancellor Helmut Schmidt, in effect, to take up the role of an indirect player at the Soviet-American talks in Geneva.

West German spokesmen sought to describe as a routine matter the reported Soviet-West German agreement to conduct regular consultations on nuclear arms control issues to be discussed at Geneva.

The agreement, however, seems to place Schmidt in a unique position -- a major Western leader with considerable influence on the shaping of NATO policies, yet the only one among his European peers to establish a separate link to Moscow on the issues crucial to the entire alliance.

The thrust of Moscow's policy on the eve of the Geneva talks appears aimed at separating the nuclear concerns of Western Europe from those of the United States.

Given Brezhnev's apparent success on this score here in Bonn, as well as the skillful propaganda drive orchestrated by his spokesman, Leonid Zamyatin, Moscow strategists appear to be shifting their rhetoric toward moderation to bring it closer to the views held by West Europeans.

Much of Western Europe has been critical of Reagan's nuclear policies. The fact that last week he finally offered a plan for negotiating arms reductions has produced a sense of relief.

Today's comments by Ponomaryov and the Literary Gazette picked up this theme.

The paper continued the propaganda struggle, but without its previous sarcasm and venom. It reported that Reagan had called for a zero option on the medium-range nuclear missiles in Europe. But then it added that the "real zero option" was proposed by Brezhnev in Bonn. It called for abolition of all nuclear weapons in Europe.

The shift in tone nevertheless seems to suggest that the Soviets are preparing for substantive negotiations in Geneva. Although they have been heartened by the antinuclear movement and have done much to encourage it, the Soviets also seem to be aware that the Europeans have become, in a relatively short time, quite knowledgeable about nuclear weapons and that propaganda slogans carry far less weight with the West European public than they did only a year ago.