Cuban President Fidel Castro has decided against an anticipated visit to New York to address the current U.N. General Assembly as chairman of the 94-national nonaligned movement.

Cuba has made no official announcement on the visit, which Castro as late as last Saturday said was still under consideration. But sources said the United Nations has been informed that a scheduled Oct. 12 speech by Cuba will be given by Vice President Carlos Rafael Rodriguez rather than Castro.

The visit would have been Castro's first to the United States since 1960, when he addressed a U.N. General Assembly remembered primarily for Soviet Premier Nikita Khrushchev banging his shoe on the table, and bear-hugging Castro in now-famous photographs.

Speculation on why Castro has decided not to travel to New York centered on three themes. Some informed observers cited severe security problems, including planned demonstrations by stridently anti-Castro exile groups.

A U.N. spokesman, however, denied that Castro would present a security risk. "We've just been through security for the pope," he said. "I think we can handle Castro. We also have a lot of people here who are not particularly popular in New York, and it's never deterred them or us."

Others speculated that both Castro and the Soviet Union, following weeks of negotiations, charges and countercharges, and President Carter's Monday night speech on the alleged presence of a Soviet combat brigade in Cuba, would now like the issue to die down.

Anything Castro might say in New York, observers said, could bring the confrontation back into the limelight.

Others noted that a backlash had already occurred at the United Nations among some nonaligned nations over Cuba's handling of the chairmanship of the organization's summit meeting in Havana last month.

A number of countries charged that Castro had misused some of the chairman's authority in an attempt to push the movement closer to the Soviet Union. One member nation, Burma, already has indicated its intention to resign from the organization for that reason. As with the Soviet troops issue, any Castro speech in New York could reopen the confrontation and serve to offset any gains Cuba feels may be made by a Castro appearance at the General Assembly.

Cuban diplomats both at the United Nations and in Washington had no comment on either the decision not to attend, or the reasons for it.

Ramon Sanchez-Parodi, chief of the Cuban Interests Section here, said he was "not able to confirm or deny" that Castro had decided not to come.

There were indications that neither Sanchez-Parodi nor the Cuban mission at the United Nations had transmitted Castro's decision, but rather that it had been conveyed to U.N. Secretary General Kurt Waldheim's office by Cuban Foreign Minister Isidoro Malmierca. Malmierca is in New York for a scheduled nonaligned foreign ministers' meeting today.

Malmierca attended Secretary of State Cyrus Vance's reception tonight for Latin American foreign ministers. A U.S. spokesman said the Cuban was in a "cordial mood."

Meanwhile, the Cuban Communist Party newspaper Granma yesterday accused Carter of trying to blackmail Castro on the troops issue, and said that Carter's Monday night speech on the subject took a "devious path of half-truths."

The Granma article was the first official Cuban reaction to the speech, in which Carter said the alleged presence of a Soviet combat brigade in Cuba presents no security threat to the United States, but outlined several military measures to counterbalance it.

Granma said Carter had contradicted himself by stating that the situation did not justify a return to the cold war, yet announcing cold war measures. By alleging that the Soviet presence contributed to tension in the Caribbean and Central America, the article said, Washington was taking measures that were designed to intimidate countries with "progressive" governments.

Echoing Castro's description of the troops issue in his news conference last Friday, Granma said that Carter had tried to "bring down a hurried final curtain on the comedy."