The Kremlin today accused President Reagan of using his appearance before the U.N. General Assembly to slander the Soviet Union and mislead international public opinion.

In a report from New York, the official Soviet news agency Tass said that the U.S. president had delivered a "hypocritical speech" that contained "demagoguery, disinformation, and blatant lies."

Ridiculing his talk about peace, it said that the "aggressive imperialist essence" of U.S. foreign policy fooled no one.

A noteworthy omission from the initial Tass report on Reagan's speech was any mention of the new U.S. proposals on limiting intermediate-range nuclear weapons in Europe. This appeared to be a sign that the Kremlim is still digesting the changes in the American position and has not yet decided how to respond formally.

Earlier commentaries in the official Soviet media dismissed western news reports of a new initiative by the United States at the Geneva arms control negotiations as a propaganda stunt.

The latest package deal suggested by Reagan still conflicts with the key Soviet objective in the talks which is to avoid deployment of U.S. cruise and Pershing II missiles altogether. But it does meet a longstanding demand by Moscow to include consideration of aircraft capable of carrying nuclear weapons.

The Soviet Union insists that it has significantly fewer medium-range bombers based in Europe than the western alliance, thus offsetting its admitted superiority in missiles. This claim, however, is denied by western military experts who insist that the Soviets have superiority in both types of intermediate-range weapons.

Moscow's definitive response to the Reagan proposals on arms control is not likely to become clear until after the Soviet leadership has had a chance to discuss the issue. The Kremlin is caught between its desire to prove its flexibility to western public opinion and its wish to show Washington that it will not be bullied into making concessions.

After a spate of "peace initiatives" that made headlines over the past year, Soviet leader Yuri Andropov has maintained a low profile since the row over the downing of a South Korean airliner by Soviet interceptor jets. The crisis over the plane destroyed the political momentum he had been building and seems to have led to a reassessment by the Kremlin of relations with the United States.

Andropov has not yet made any direct comment on the plane affair. Today he sent a formal message of greetings to a conference of Asian and African writers in Tashkent in which he attacked the "big stick" policy that he said was being employed by the Reagan administration against the Third World.

The message said that the threat of "nuclear catastrophe" had increased and blamed what it called the "unprecedentedly militarist preparations" of the United States and the North Atlantic Treaty Organization.

Tonight's Tass commentary on Reagan's speech also concentrated on attacking U.S. policies in Africa, Asia and Latin America, the areas of the world that hold a majority of seats in the General Assembly. It blamed U.S government "initiatives" for the increasing level of violence in such countries as Lebanon, Chad and El Salvador.

Tass said that the address reflected Reagan's annoyance at the widening rift between the United States and the Nonaligned Movement.

The Tass reaction seemed almost mild and routine compared to some of the language that has been used against the U.S. administration in the past few weeks.

Soviet officials had been braced for sharp rhetoric from Reagan over the plane tragedy in the General Assembly and may have been surprised at being let off relatively lightly.

The Tass report said that Reagan had made "an awkward attempt to excuse himself for the public attacks" on the United Nations by official U.S. representatives. The Soviet media have accused the United States of showing contempt for the world body and failing to fulfill its obligations as the host country.

Soviet Foreign Minister Andrei Gromyko canceled plans to attend the General Assembly session after his plane was refused landing rights at civilian airports in the New York area.

Soviet officials have said the gesture was also intended as a signal to Washington of Moscow's ability to withstand diplomatic pressures.

Gromyko has attempted to drive the point home by maintaining an active schedule in his absence from New York. He has received visitors from other Soviet Bloc countries and today began talks with the foreign minister of Czechoslovakia.