President Reagan gave his moral and political support yesterday to a group of exiled Soviet dissidents he invited to lunch in the White House.

Just two days after announcing his desire for "dialogue" with Soviet leaders on a new strategic arms control agreement, Reagan told his eight guests--symbols of an internal opposition reviled by the Soviet leadership--that he wants to help those struggling for human rights in the Soviet Union.

The timing was a coincidence. The lunch was scheduled weeks before the president knew he would be speaking on arms control at Eureka College last Sunday. But White House officials said Reagan was not embarrassed about entertaining Soviet dissidents just as he launches new arms talks.

Seven years ago, another Republican president, Gerald Ford, refused to invite Alexander I. Solzhenitsyn, the Nobel laureate, to the White House for fear of angering the Soviet leadership.

Reagan sought to undo that snub by including Solzhenitsyn in yesterday's lunch, but the writer, now a resident of Vermont, declined. Solzhenitsyn told the White House that he considered it inappropriate for a writer to attend a luncheon with people he described as politicians and professional emigres.

Members of the group who accepted the invitation said after the lunch that they had received a warm reception from the president, Secretary of State Alexander M. Haig Jr., White House Chief of Staff James A. Baker III, national security adviser William P. Clark and other officials.

Pavel Litvinov, a former human rights activist in Moscow and the grandson of Maxim Litvinov, once Joseph Stalin's commissar for foreign affairs, told reporters that Reagan "reaffirmed his position" in support of human rights and said he planned to do more to try to improve the situation inside the Soviet Union.

Reagan closed the lunch by reading a brief statement that the White House declined last night to make public.

According to participants in the lunch, it was a general statement of concern and support for human rights activists in the Soviet Union.

The president twice quoted Andrei D. Sakharov, the nuclear physicist and dissident leader now confined in forced exile in the Soviet city of Gorky.

Valery Chalidze, a physicist and colleague of Sakharov in the Soviet Union, said the group had discussed the possibility of Reagan raising the human rights issue when he meets with Soviet President Leonid I. Brezhnev.

Reagan gave no concrete promises on this score, Chalidze said.

Other participants said Reagan told the group he believes in "quiet diplomacy" rather than confrontational public demands on Soviet leaders.

But he also said that public pressure from members of Congress and others could help make quiet diplomacy more effective, they said.

Reagan told the group about the letter he had written to Brezhnev in his own hand while he was recuperating from the attempt on his life last year, and he expressed disappointment in Brezhnev's reply, which seemed formal and propagandistic, the president said.

Reagan asked the dissidents if they thought Brezhnev himself had written the letter; the answers were mixed.

Reagan heard personal statements from most of his guests and was visibly moved by their accounts of persecution and prison terms, participants said.

The lunch began with a prayer by Pastor Georgi Vins, a Baptist activist whom the Soviet regime had imprisoned.

Vins gave Reagan a copy of the tiny copies of the Bible that prisoners were able to hide from their guards in Soviet labor camps.