For months now, Kremlin leader Mikhail Gorbachev has been taking to the Soviet airwaves in a series of rambling speeches, sounding like a man exhausted by the job of trying to build a new society in a landscape of collapse. Yesterday, American audiences got a chance to see Gorbachev in this new and tired incarnation.

Although Gorbachev was his old energetic self at times, jumping out of his limousine to work the crowds on New York Avenue, he was also defensive, elusive and disjointed, especially in a lunchtime speech at the Soviet Embassy. He seemed particularly perturbed that Soviet and American commentators are talking freely now about the Soviet Union's increasingly weak position in the world. He warned against anyone trying to apply pressure on him or on the Soviet Union because they think it's "enfeebled."

"All the instability, all the changes, are just an indication of the fundamental nature of reform," Gorbachev said. Talk of weakness, he said, "is just not serious."

Last night at the White House, he seemed to be warning Americans that he needed their help. "We have not yet completed the task of creating a durable democratic system in our country," he said in his after-dinner toast, adding that he was confident this goal would be achieved.

As a politician praised for his theatrical flair for rhetoric and improvisation, Gorbachev yesterday could not match the performance he gave when he hosted a similar session here in 1987. Although he tried to repeat his customary routines, flattering his guests by name and breaking into a broad grin, the embassy luncheon had the feel of a not-quite-successful revival.

In those euphoric days of 1987, when Gorbachev could dazzle a crowd with a wave and Soviet political life was a matter of pro- and anti-reform, writers who met him would rhapsodize about the Soviet leader's intelligent eyes and his ability to mention the book titles of the various guests.

And last time, Gorbachev appealed for policies that would "express the mood of the people," and the mood of Moscow was still hopeful. But now Gorbachev finds himself in a position where politicians criticize him for being too slow and too cautious, and the mood of the people is angry, dispirited and cynical.

Henry Kissinger pronounced Gorbachev as "serene" in manner at the embassy, but Gorbachev actually seemed a bit testy as he reflected on the criticism abroad that the Soviet Union has not gone far enough to reform the economy: "For Americans, it is all so easy. You have all the mechanisms and institutions in place." But in the Soviet Union, where there has not been anything resembling a market economy in decades, people still think of markets as "speculation."

"Oh, how we have to twist our brains!" he groaned.

To an American audience Gorbachev's speech before the trays of caviar arrived may have seemed almost disturbingly disjointed. But this style of free association, leaping from a glancing economic analysis to flattering someone in the audience, is well-known to Soviet viewers who still follow Gorbachev's frequent appearances on television. Gorbachev seemed so pressed to cover all his points that his syntax made George Bush's speeches seem as smooth as the prose of Genesis.

For Gorbachev, America is a relatively easy room to work. Although he referred to the embassy audience as intellectuals, the audience looked less like the editorial board of Partisan Review than a banquet at the Polo Lounge. And unlike the audiences in Moscow, which have begun to test Gorbachev's patience by challenging him on every conceivable point, from the wisdom of socialism to the need for a Lenin Mausoleum, the Americans spent no time on criticism.

After lunch, several of the guests rose to speak, "but all they did was praise Gorbachev and tell him to keep doing what he is doing. There was not one sharp question," said Dmitri Likhachev, a cultural historian from Leningrad and a former prisoner in Soviet labor camps.

Likhachev was taken aback, as well, by the small number of serious writers and artists in the room compared to the number of movie stars. Science fiction authors Ray Bradbury and Isaac Asimov represented the world of creative writing because, as the Soviet leader explained, they "are my daughter's favorite authors."

"There were a few writers there, but with all those movie stars around I admit it was an odd bunch to be called 'intellectuals,' " Likhachev said. "I guess not everyone knows what intellectual means." A White House source said Soviet officials in Moscow drew up the guest list and that Gorbachev's wife, Raisa, had especially asked to meet some Hollywood stars.

"I felt that we had to meet with members of the American intellectual community, because it is indeed the stuff of which a society is made," Gorbachev said.

There were some bona fide academics amid the stars: economist John Kenneth Galbraith, Georgetown University President Leo J. O'Donovan and physicist Roald Sagdeev. Jesse Jackson was the only politician in the room. The representative of religious life was televangelist Robert Schuller, who will broadcast a series of religious homilies on Soviet television this year.

Four blocks down 16th Street, Raisa Gorbachev seemed pleased to be at a White House without Nancy Reagan. Not only did she get along with the Bush family, she was a hit with the family's springer spaniel. "Mrs. Gorbachev and Millie bonded," Barbara Bush's spokeswoman said, adding that the dog "quivered with excitement whenever Mrs. Gorbachev spoke to her."