The Soviet Union leveled a bitter, cold war-style attack at the United States today, accusing President Carter of "bellicose and wicked" distorions of the Kremlin's intervention in Afghanistan and charging Carter with using it as a "pretext" for postponing ratification of SALT II.

In a brief dispatch from Washington shortly after Carter announced his decision to seek Senate delay of a vote on the treaty, the official Tass news agency said the administration and "rectionary quarters" in the United States seeking to escalate the nuclear arms race had been atempting for some time to delay a ratification vote.

Tass did not say what the Kremlin may do in response to the SALT delay. Moscow and Washington currently abide by the expired terms of the original SALT I treaty. The natural parliament, the Supreme Soviet, has not officially ratified SALT II, but that is only a fromality.

Soviet sources here today made clear that they believed the Kremlin had foreseen the possibility of a treaty ratification delay when forecasting the probable American reaction to its venture in Afghanistan.

[In Kabul, diplomatic sources said Soviet forces fanning out from the Afghan capital have reached several provincial cities. But reports from the area are still sketchy because Afghan authorities are refusing to allow Western reporters to stay in the country. Details on Page A12.]

The Soviets also accused the United States of using the Central Intelligence Agency to plot an alleged assassination attempt against U.N. Secretary General Kurt Waldheim earlier this week in Tehran.

The Soviet propaganda assault reached new heights today as Moscow sought to blunt mounting anger in foreign capitals. Official Soviet sources here have indicated extreme nervousness over NATO deliberations on retaliatory actions against the Soviets that include cutting trade and cultural contacts and a possible move to boycott the 1980 Olympics in Moscow. c

But Tass aimed its most bitter tirades against Carter, who in a New Year's Eve television interview questioned the veracity of Soviet President Leonid Brezhnev's explanation of the Soviet military incursion. Carter said Brezhnev's version of events leading up to the intervention had caused the president to reassess Kremlin motives and goals around the world.

Without mentioning Brezhnev, Tass declared that in a "bellicose and wicked" interview, the president maliciously attacked the Soviet Union's policy, distoring its essence and meaning. He spoke about some Soviet invasion of Afghanistan and threatened serious political consequences and actions." Tass said the Western outcry against the Soviet intervention broke "all records of hypocrisy and lies."

Extended, authoritative Moscow comment on the president's decision on SALT is likely to expand these themes in coming weeks. U.S.-Soviet relations have reached a new low following last Thursday's Soviet military move that toppled leftist Kabul leader Hafizullah Amin and installed Babrak Karmal, a Marxist who was even more pro-Soviet. Moscow has always maintained that SALT was too important to world peace to be "linked" to other international issues.

Tass also declared that the "frenzied propaganda ballyhoo" of the Western nations and NATO deliberations on possible retaliation were designed to "distract world attention from the foul schemes and deeds of the imperialist powers."

The agency accused Washington of trying to "camouflage" its military threat to Iran by creating an outcry about an "invented" threat to Iran posed by the Soviet presence in neighboring Afghanistan. Tass also accused NATO of using the Afghan incursion as an excuse to include the Middle East in its purview and to deflect public opinion in Europe from the recent decision to deploy advanced U.S. nuclear missiles in Western Europe.

The Soviets today reiterated charges that Amin had been a CIA agent. Furthermore, in a dispatch from Tehran, Tass said the alleged assassination plot against Waldheim "should be viewed in close connection" with Iranian Islamic leader Ayatollah Ruhollah Khomeini's charges that U.S. intelligence agency is trying to destabilize Iran. Tass said the reported plot bears "circumstances resembling those in which then-U.N. secretary general Dag Hammarskjold" died in the Congo in 1961. Hammarskjold died in a plane crash during peacemaking efforts in the Congo.

Soviet sources today said their troops in Afghanistan are under strict orders not to fire unless fired upon, and that their tasks are "defensive" only. Soviet television has shown no scenes from the streets of Kabul, although a news interview with a Karmal government figure was shown on television tonight in the peaceful setting of an office.

Reports in other Soviet media as well as the Tass commentary seemed to denote a shift in the official approach to the Afghan rebels, whom Karmal sought to pacify in his first public statements seeking peace in the countryside. Kabul correspondents for the Communist Party newspaper Pravda and the government paper Izvestia quoted peasants as saying the rebels now are killing people who support Marxist reforms of the country.

Tass called the Moslem insurgents "fanatical bandits who in their fury and frenzy burn whole villages to the ground, massacre whole families, put out eyes and cut off the hands of activists . . . without sparing old folk, women and children." Tass said Western silence about such atrocities puts the "brutal murders under their protection."

The descriptions appear to be an expanded attempt to justify direct fighting between Soviet troops and the Moslem insurgents. The Soviets have never officially made any direct reference to the number of their troops in Afghanistan, now estimated by Washington at 30,000 to 40,000, although both Pravda and Izvestia have said there have been armed clashes in remote areas.