Soviet leader Mikhail Gorbachev is unlikely to come to the United Nations next fall, removing the occasion for an easily arranged meeting with President Reagan this year, informed sources said yesterday.

A White House official said "signals" that Gorbachev does not intend to travel to the United Nations soon were received in Vienna last week when Secretary of State George P. Shultz met Soviet Foreign Minister Andrei Gromyko.

Other sources made no reference to the Shultz-Gromyko meeting but said they understood a visit to New York by Gorbachev is now not expected.

For several months the Reagan administration's working assumption has been that Gorbachev would probably come to New York in September or October for the U.N. General Assembly session, providing an easy opportunity for a limited meeting with Reagan in New York or a more extensive and important meeting with him in Washington.

On April 22 Viktor Afanasyev, editor of the Communist Party newspaper Pravda, told Reuter news agency in Moscow that Gorbachev would come to the United Nations this fall and might well meet Reagan at that time. Reagan as late as a May 10 news conference described a Gorbachev visit to the United Nations as "probable" though he also said there was "no confirmation."

A U.N. official said the "general impression" there, gleaned in part from Soviet diplomats, had been that Gorbachev was likely to come. But nothing has been heard lately, the official added, and no formal word has been received from Moscow at any time.

In his May 10 news conference, the president tied an early meeting with Gorbachev closely to the U.N. appearance. Reagan said he extended an invitation to Gorbachev that, "if he was going to be here, the door was open for a meeting between us." Reagan added that "the ball is in his court, first, to decide whether he's coming here. And then, second, as to time and place for such a meeting if he is willing."

Following the six-hour Shultz-Gromyko meeting in Vienna last Tuesday, however, White House officials began to separate the question of a Reagan-Gorbachev meeting from that of a Gorbachev visit to the United Nations.

Defense Secretary Caspar W. Weinberger said in an NBC television interview Sunday that "it may well be that the Soviets are backing off a bit" from an early Reagan-Gorbachev meeting. Weinberger added, though, that "it's hard to tell now . . . . It's just a little early to say."

U.S. officials have gone out of their way to say in recent days that Reagan's invitation to Gorbachev refers specifically to a meeting in Washington. According to diplomatic protocol, officials said, it is the U.S. leader's turn to play host since the last superpower summit on the soil of either country was President Gerald R. Ford's meeting with Soviet leader Leonid Brezhnev in Vladivostok in 1974.

Presidents Ford and Carter met with Brezhnev later on the neutral ground of Helsinki and Vienna, respectively.

Should Gorbachev suggest a meeting on neutral ground rather than in Washington, there would be "no warm feeling" in the administration for such a proposal, a White House official said. He declined to rule out such a meeting, however.

While the summit is problematical, U.S.-Soviet meetings at lower levels are likely to occur in the coming months.

Shultz and Gromyko may meet again in Helsinki around Aug. 1 on the occasion of the 10th anniversary of the signing of the 1975 Helsinki accords.

U.S. and Soviet experts on Afghanistan and southern Africa are likely to continue a pattern of talks. Such official talks on Afghanistan were held in 1982 in Moscow, and those on southern Africa in 1981-83 in New York, Geneva and Moscow.

U.S.-Soviet expert-level talks on the Middle East were held Feb. 19-20 in Vienna.