The Soviet leadership sharply rebuked Sen. Edward M. Kennedy yesterday for publicly suggesting that as a result of recent meeting with President Leonid Brezhnev, the Kremlin would probably grant exit visas to 18 families seeking to leave the Soviet Union.

A commentary in the Communist Party newspaper Pravda, while not mentioning Kennedy by name, left no doubt about its target as it took to task "bourgeois politicans" who attempt to create "the impression that attempts to intervene in the Soviet Union's internal affairs can be more successful if the methods of so-called quiet diplomacy are used."

The commentary did not say the 18 families - which include a prominent Jewish scientist, Benjamin Levich, and his wife - would continue to be denied permission to emigrate. But several of those affected expressed pessimism over their chances last night in view of the Pravda attack.

In Washington, Kennedy declined comment on the Pravda commentary. But his press spokesman, Tom Southwick, said, "We continue to have every expectation that the assurances received by the senator in Moscow still hold."

Some Western diplomatic sources here were puzzled by the Pravda outburst. It was known when Kennedy departed last Sunday that he intended to announce publicly his belief that the leadership had agreed to review the cases of some of the Jewish families, called "refusedniks," whose exit visas have been denied for many years.

It was believed here that Kennedy would not have had such intentions if his Soviet hosts had not known of them, and tacitly approved.

But other sources recalled how in 1974, after the Soviets agreed privately to accept a link between immigration of Jews and U.S. trade benefits for Moscow, Sen. Henry Jackson disclosed the deal to reporters. The Soviets thereupon denied that the bargain had ever been made.

Conceivably, the Kennedy case may be a similar instance of Kremlin anger over a concession being made public.

The Pravda commentary, headlined "Rejoinder," said "pronouncements of some politicians of the United States, including congressmen, have appeared again in the American press in the past few days on the possible departure from the U.S.S.R. of a number of persons who expressed the desire to move to Israel or the United States."

"Whatever the motives behind the desire of this or other leaders to pose as a champion of human rights - and no matter how alluring such a possibility would seem to him - the essence of the matter does not change," the commentary said.

"Those who entertain some illusions on this score should know that neither in these matters nor in politics in general does the Soviet Union have a double standard - one policy designed for the public and the second for some other occasions.

"Such phenomena may not be a rarity for bourgeois politicians - but there exist generally recognized international standards, and, in the final analysis, simple tact which they should also observe."

Some sources also took the view that the commentary as a retort to a Washington Post editorial that said Kennedys visit showed that if treated tactfully, the Soviet Union could be more flexible on human rights.

Kennedy, at his news conference earlier this week, said "the most important tangible result" of his visit to the Soviet Union, which included a two-hour meeting with Brezhnev, came in discussions concerning families seeking to emigrate to the United States and Israel.

"I am pleased to be able to report that the Soviet government has already agreed to reconsider the cases of 18 specific families," Kennedy said. "I have every expectation that all of these families will be permitted to leave for the United States or Israel in the very near future."