The presidential commission on AIDS is scheduled to meet for the first time today amid threats of disruption by gay-rights activists and facing a challenge to its composition by the American Civil Liberties Union.

The 13-member panel, appointed by President Reagan to advise him on the "medical, legal, ethical, social and economic impact" of the disease, has been criticized by public health officials and gay-rights groups for its collective lack of knowledge about acquired immune deficiency syndrome and the strong views of several members that diverge sharply from accepted scientific evidence.

In a letter sent to the White House yesterday, attorneys for the ACLU and the Public Citizen Health Research Group charged that the commission violates the Federal Advisory Committee Act, which requires such commissions to be "fairly balanced in terms of points of view" and include representatives of groups most affected by its work.

The AIDS commission contains neither AIDS patients, those who care for them, persons engaged in research about the disease nor those familiar with the problems of intravenous drug abusers.

William B. Rubenstein, staff attorney for the ACLU, called on Reagan to appoint immediately at least four new members to balance the "very extreme views" of four of the panelists.

They are: Theresa Crenshaw, a San Diego sex therapist who has said AIDS might be transmitted casually through saliva or on toilet seats; Penny Pullen, an Illinois state legislator who has accused public health officials of "bowing to the political clout of organized homosexuals"; Richard DeVos, president of Michigan's Amway Corp., who says he thinks the gay community has demanded rights but acted irresponsibly to prevent the spread of AIDS; and Dr. Cory Servaas of Indiana, whose mobile AIDS testing van has been criticized by federal health officials for notifying people of test results by mail.

White House spokesman B.J. Cooper said officials there had not seen the letter. "The commission was appointed with a good range of views and the resources to do its job," he said.

Although this is the commission's first official meeting, some members have traveled to New York City and San Francisco to meet with AIDS patients, AIDS workers, public health officials and to tour hospitals and counseling centers.

During a tense meeting last week with members of San Francisco's gay community, Dr. W. Eugene Mayberry, chairman of the commission, said he understood the concern but said that the "commission is not constituted to render moral verdicts. . . . Don't judge us too quickly," he said.

Tim Sweeney, deputy executive director for policy of the Gay Men's Health Crisis in New York City, said a five-member delegation including DeVos spent two days in Manhattan last week on a similar tour.

"We wanted to give them a human sense of AIDS," said Sweeney, who arranged a meeting with a coalition of community groups, including Mothers of AIDS Persons. "We've made it very clear that we intend to watch what they're doing very closely."

Mayberry and other commission members have expressed concern that the two-day meeting may be disrupted by gay-rights activists. Officials of several New York-based groups say they have chartered buses from New York and plan to demonstrate outside the National Press Building, where the hearings will be held.