The governing board of Washington's exclusive Cosmos Club, which had threatened to suspend or expel the leader of a movement to admit women to the all-male bastion, has formally warned him against creating "friction" but did not take disciplinary action against him, according to club sources.

The board last September threatened action against Samuel P. Hayes, 75, a retired economist who is chairman of the group pressing the women's issue. The board accused him of "ungentlemanly behavior" in a list of charges that included spreading misrepresentations, using "strident language" and "pestering members."

Hayes, in a formal response to the board, denied the allegations, asserting that the board singled him out for discipline because of his views, not because of his behavior. Several other members, angered by the charges, said Hayes was "a gentleman" and one called the charges "rubbish."

The move ignited passions on both sides of the dispute over women's membership that has raged at the club for more than a decade. Yesterday, in a supplement prepared for mailing with the club's newsletter, the board broke with tradition by making public its actions, without actually naming Hayes, according to sources. The sources said it was widely understood the article alluded to the Hayes affair.

According to sources, the board announced that it had sent a "cautionary letter" to a member, informing him that some of his conduct has been "unacceptable." The board also stated it hoped and believed no other action would be necessary.

In a personal letter from the board, sources said, Hayes was warned against creating "friction" at the club.

Both Hayes and Bruce Clubb, vice president of the Cosmos, declined yesterday to discuss the board's action.

Members of the club, which operates in an ornate Embassy Row mansion at 2121 Massachusetts Ave. NW, have twice rejected proposals to admit women as members since the issue was first raised in 1971. But the group now led by Hayes, which claims the support of more than 450 of the club's approximately 3,200 members, has kept the issue alive.

One member who favors the admission of women said yesterday that the board has "continued to totally misrepresent the facts by saying Hayes' behavior is ungentlemanly or that he has caused friction. He is the most gentlemanly, courtly man we know. The only people who have transcended the bounds of decency and been confrontational is the board of management itself."