Although the Soviet Union has met President Reagan's recent call for superpower compromise with a barrage of public verbal assaults against Washington, some Soviet officials say privately that a new impetus in both capitals provides the rough framework for improved relations between the Reagan administration and Moscow.

In a speech Thursday in Glassboro, N.J., Reagan said the Soviet Union had now "begun to make a serious effort" toward nuclear arms reductions with its most recent proposals put forward at the strategic arms talks in Geneva. He cited "fresh developments" and a "moment of opportunity" in relations with Moscow and talked of a possible "turning point in the effort to make ours a safer and more peaceful world."

The speech reflected a positive, but minor, shift in Washington's Soviet policy, according to several Soviet officials here, who asked not to be identified. "But its effects here will depend on whether and how strongly Reagan follows it up," one expert on the United States said.

Georgi Arbatov, director of the U.S.A. and Canada Institute, and some other Soviet officials have said in recent interviews that they recognize pressures in Washington to backtrack from a policy of confrontation toward the Soviet Union.

However, leading Kremlin official Yegor Ligachev and the Soviet media have continued to assail the Reagan administration's policies as anti-Soviet, militaristic and uncompromising. The Glassboro speech was not reported in the Soviet media.

Western diplomatic sources here consider Reagan's Thursday speech and the June 11 strategic proposals put forward by the Soviets in Geneva as mood-setting devices for the summit meeting between Reagan and Soviet leader Mikhail Gorbachev, which the two agreed to hold in the United States this year. No date or final agreement, however, has been set.

The Soviet proposal for reductions in the nuclear warheads on both sides struck western arms experts here as more realistic than earlier Soviet arms packages, which one described as "pie in the sky."

The positive tone of the Glassboro speech, held in the same place as the 1967 summit meeting between President Lyndon B. Johnson and Soviet Premier Alexei Kosygin, appeared to help satisfy Moscow's demand for an improvement in the superpower atmosphere before plans for the Reagan-Gorbachev meeting can be made, the diplomats said.

But a day after Reagan gave the speech, second-ranking Politburo member Ligachev launched a blanket attack against the Reagan administration's policies toward the Soviet Union in a speech here to deputies of the Supreme Soviet.

"The U.S. administration is ignoring the peace proposals of the Soviet Union," Ligachev said Friday, "and responded to them with acts of aggression against Libya and fresh acts of provocation in Nicaragua, the Middle East, Angola and Afghanistan," according to a report by Tass, the official Soviet news agency.

Ligachev, echoing the Kremlin's line of fire against Washington, charged the Reagan administration with "launching a new arms race" and "hoping to drag the Soviet Union into it."

Ligachev did not refer to Reagan's conciliatory remarks in Glassboro, but in a dispatch yesterday, Tass said they were "stuffed with anti-Soviet cliches." Tass also accused Reagan of covering up a massive rearmament campaign with propaganda.

In a statement to the Socialist International congress in Lima, Peru, released by Tass, the powerful Communist Party Central Committee sharpened the Kremlin's rebuke of Reagan's recent denunciation of the unratified SALT II treaty on limiting strategic weapons and the U.S. refusal to join Moscow's moratorium on nuclear testing.

The United States has embarked "on the course of heightening confrontation, building up armaments without restraints, and attaining military superiority," the statement charged.

In a commentary also not in keeping with Reagan's speech at Glassboro, the military newspaper Red Star yesterday accused the U.S. president of launching "an unpredecented arms race and a campaign of anti-Soviet lies and slander."

Arbatov and other Soviet officials were critical of the Reagan administration's stance on SALT II, but also said that, in their view, some U.S. officials appeared to realize that the Reagan policy had become detrimental to U.S.-Soviet relations and U.S. interests.

Arbatov, in a recent interview, said he has only detected a policy of "continuing the arms race" emerging from Washington in the past month.

Despite the Reagan administration's harshly critical approach to Moscow, Arbatov said, "the government was sure that the Russians would creep on their knees to Washington, whatever the Americans do."

"This has to fail sometimes," he continued, "and I think that now some people understand that they overdid it."

Still, Arbatov said of the Reagan administration: "I don't know what kind of summit they plan, a funeral summit, a funeral for SALT II, and for all other elements of arms control." Calling on Washington to restore its commitment to SALT II, Arbatov said, "From our part, the door is open for positive development in American policy."