Defense Secretary Caspar W. Weinberger, in an interview published today in a West German newspaper, criticized former chancellor Helmut Schmidt for doubting the Reagan administration's commitment to arms control.

Weinberger's statement, quoted in Die Welt, caused considerable comment at a meeting of foreign policy makers that Weinberger addressed tonight. Weinberger said Schmidt's position, expressed in an earlier interview with The Washington Post, does "an extreme disservice" and "seems to be an attempt to change positions" from Schmidt's earlier commitment to support putting U.S. intermediate-range nuclear missiles in West Germany in December.

In his remarks tonight, Weinberger also said the Soviet Union has increased its deployment of intermediate-range SS20 missiles from 351 to something "well above" that figure, possibly in the 360s. The deployment of SS20s, many of them aimed at Western Europe, is the impetus cited by NATO for its planned and controversial basing of sophisticated nuclear weapons, 572 Pershing II and low-flying cruise missiles, in Europe.

Weinberger said that many of the new SS20s have been installed east of the Ural Mountains, beyond the range of Western Europe. But Weinberger said the missiles are so mobile that where they are deployed is of little consequence.

Although it is not the stated purpose of his trip to West Germany, Norway and a NATO defense ministers' conference in Belgium, Weinberger is devoting considerable energy to ensuring that NATO retains "the capability, the will and the resolution" to go forward with next winter's missile deployment.

He told a generally receptive audience of more than 400 members of the German Foreign Policy Society that only the planned deployment of missiles has given the Soviets incentive to bargain for arms reductions. Weinberger adopted a reassuring tone, however, promising his audience of Cabinet ministers, former ministers and other dignitaries that President Reagan "is personally and deeply committed to reducing nuclear weapons." He twice departed from his prepared text to promise that the United States is not seeking nuclear superiority.

Nonetheless, he faced a number of skeptical questions about Reagan's commitment to arms control, about the president's harsh rhetoric--in particular his characterization of the Soviet Union as an evil empire--and about Weinberger's past statements about fighting "a protracted nuclear war." He was also asked about Schmidt's suggestion that the United States is not truly committed to arms control negotiations.

In the newspaper interview, Weinberger called that suggestion "absolutely incredible." Last night he avoided any challenge to Schmidt himself--"I would be very hopeful that that was a misquotation," he said--but reiterated the administration's commitment to arms reductions.

"There is nothing whatever to the suggestion that we have been insincere or laggard or indeed ineffective in our proposals," Weinberger said.

Schmidt's comments fueled speculation here that his Social Democratic Party, now in opposition, would repudiate the missile basing, as Weinberger himself suggested Schmidt might be preparing to do.

Last week in Denmark, which belongs to NATO but is not slated to receive any missiles, the parliament voted in favor of delaying the scheduled deployment. Weinberger was asked whether the nuclear "modernization" program might cause a rift in the NATO alliance.

"I think it's significant that no deployment of nuclear missiles was planned for Denmark," Weinberger responded. "In the countries where deployment has been planned, the governments have uniformly supported deployment . . . . I have sensed no cracks in that unity."