oviet President Leonid Brezhnev has sent a personal message to President Reagan calling for urgent action to prevent what he called "the continuing annihilation of people in Beirut" by Israeli troops, the Tass news agency reported today.

It was the second time in less than a month that the Soviet leader has appealed directly to President Reagan over the fighting in Lebanon. But, like the earlier message, the latest appeal was vaguely worded and contained no hint of Soviet countermeasures should the fighting in Beirut continue.

The White House today rejected what it called the implication in the letter from Brezhnev that the United States is not doing everything it can to resolve the Lebanese crisis.

Deputy press secretary Larry Speakes read a presidential statement to reporters aboard Reagan's plane during a trip to Des Moines, that said, "We reject the implication contained in President Brezhnev's letter that the United States is not doing all it can to bring about a peaceful solution to the crisis in Lebanon."

Western diplomats speculated that the main purpose of Brezhnev's well-publicized messages was to establish a legitimate Soviet concern about developments in the Middle East and win propaganda points from the Arabs.

Summarizing Brezhnev's message, Tass said he wished to draw Reagan's attention to "the perfidious actions of Israel," which have resulted in peaceful inhabitants of Beirut being "ruthlessly killed."

Tass said that Brezhnev "called on the president of the United States to use most urgently the possibilities at his disposal to stop the continuing annihilation of people in Beirut." The message was reported to have described the situation as "so serious and critical that the adoption of the promptest measures is necessary."

The Soviet news agency did not say when the message was delivered to Reagan. But its wording gave the impression that it was prompted by last weekend's attack by Israeli troops on Palestinian guerrillas trapped in West Beirut.

While the Soviet Union has refrained from any direct involvement in the latest Middle East crisis, it has been fiercely critical of what it sees as U.S. support for Israel. Soviet news media, in an apparent attempt to secure maximum propaganda advantage, have attacked U.S. identification with Israeli interests and the supply of American weapons to Israeli forces.

According to Tass, Brezhnev said that "the tragedy of Lebanon . . . will remain an indelible stain on the conscience of those who could stop the aggressor but did not do so." This was a clear reference to the United States.