President Leonid Brezhnev guardedly endorsed the election of Stanislaw Kania as Poland's Communist Party first secretary today in a brief messge that combined Soviet misgivings about his leadership with hopes for an end of the turmoil within the Polish party.

Its curt tone and the absence of personal compliments were in marked contrast to Brezhnev's greeting to Kania last September, when he was first chosen party leader. At that time Brezhnev addressed Kania as "dear comrade" and praised him as a man of courage and a "staunch" Communist.

Today's congratulatory telegram was addressed to "respected comrade Kania." It made no references to the Polish party congress, the first freely elected congress in the Soviet Bloc, nor did it contain the standard best wishes for success in building socialism.

According the official news agency Tass, the message said: "I congratulate you on your reelection to the post of first secretary of the Polish United Workers' Party. I am sure that the fraternal friendship linking the Soviet Communist Party and the Polish United Workers' Party will continue to grow stronger on the principles of Marxism-Leninism and socialist internationalism."

The message -- the first authoritative Soviet comment on the Polish party congress -- was intepreted by Western and East European observers here as a signal that, at least for now, Moscow has grudgingly accepted the changes in the Polish party.

According to this view, the Soviets hope to see restoration of the Polish party's authority in the country even if moderate, reformist leaders appear to be in charge there.

Brezhnev's messge came after a few weeks of surprising silence about a congress that is considered as crucial for the Soviets and their other allies as it is for the Poles.

The Communist Party newspaper Pravda today made the first and somewhat ambiguous referene to the secret ballot used in selecting the Polish Central Committee. It did not tell its readers that there was a choice of candidates.

The Soviet party's rule also calls for secret ballot, but there is no choice of candidates.

The Soviet press has carried no substantive news about the congress except when it quoted speakers with views similar to those held in the Kremlin. The main part of coverage focused on three speeches made by Viktor Grishin, the chief Soviet delegate attending the Polish congress.

So far, the Soviet public has not been told anything about the turnover in the Central Committee or other issues that represent a radical departure from the Soviet style of "democrati centralism."

Grishin's speeches were carried in full and contained standard Soviet positions. But their tone was restrained and seemed tailored to portray events in Poland as not out of hand.

This is unusual and a clear indication that the Soviets are still not sure how things will turn out. Until four weeks ago the Soviet press described the situation in Poland in every more threatening terms that culminated in a blunt warning letter to the Poles.

Since the visit to Warsaw of Foreign Minister Andrei Gromyko, however, the Soviet media has dropped its threats and largely ignored the Polish situation. If displeasure was voiced here, it was done in an oblique way by printing critical East European dispatches or by quoting hard-line Communists in Poland.

Last night, for instance, Moscow television featured Albin Siwak, a Warsaw construction foreman and delegate to the congress who attacked the independent trade union federaton Solidarity and warned of trends toward anarchy in the party.

Western observers here said the coverage of the congrss suggests that the Kremlin wanted to put a better face on the more troubling developments without endorsing them