Groups that compete in the Combined Federal Campaign, the government's annual charity drive, are complaining that new Reagan administration efforts to bar advocacy groups could make all charities ineligible to solicit contributions from federal workers through payroll deductions.

Nonprofit organizations as divergent as United Way of America, the Sierra Club Legal Defense Fund and the American Heart Association argue that recently imposed CFC restrictions, which deny eligibility to groups that lobby or litigate on social policy issues, are too broad and would violate their First Amendment rights.

But the groups, whose squabbling over access to federal payroll deductions has been termed the "charities war," differed sharply at a House subcommittee hearing last week on just who should be in or out of the government's $100 million charity drive.

Restrictions on CFC participation were contained in an executive order issued by the president last month. They are intended to limit CFC eligibility to traditional health and welfare groups that provide direct charitable services and bar participation by single-issue advocacy groups that try to influence public policy.

Advocacy groups currently participating in the CFC range from the Women's Legal Defense Fund and the New York-based National Black United Fund to the Conservative Legal Defense and Education Fund.

Traditional charity groups have long argued, particularly as the CFC has grown larger and more competitive, that the government's charity drive ought to exclude advocacy groups. Their only complaint with the Reagan order is that it has gone too far and could affect their own charity organizations, since they also lobby and take public stands.

"This would mean the Red Cross couldn't urge people to give blood or a Boy Scout executive couldn't declare his political affiliation when he registers to vote," Ernest Miller, a Salvation Army spokesman representing a coalition of health and welfare organizations, told the House subcommittee on manpower and housing.

The administration has sought to allay their concerns, all but promising that regulations implementing the executive order--which have not yet been issued--will allow groups to lobby on behalf of themselves. Only the political advocacy groups will be ousted from the CFC, according to Donald J. Devine, director of the Office of Personnel Management, whose agency administers the charity drive.

Underlying the eligibility debate, according to the advocacy groups and administration critics, are questions about what constitutes a true charity and whether a group's controversial nature--or confrontational tactics--make it any less deserving of CFC participation.

"Do you do more to fight cancer by harassing the EPA than by urging people to have checkups?" asked Rep. Barney Frank (D-Mass.), subcommittee chairman, who challenged any suggestion that one group of charities is more important than another. "That's not a decision government should make."

But Devine and representatives of traditional charities said the drive had been hurt by inclusion of advocacy groups, especially the addition last year of the National Right to Work Legal Defense and Education Fund, which sparked a partial labor boycott of the campaign.

"It's a question of priorities," said Jack Moskowitz, senior vice president of the United Way of America. "We believe it's good management to limit the campaign to health and welfare groups."

Advocacy groups, fearing they are about to be kicked out of the drive, point out that it was only a year ago that the administration issued CFC guidelines it heralded as opening up the campaign to a wide variety of groups.

"It's been shown time and time again that when you give employes more choice of charities to support, they give more money," said Robert Bothwell, executive director for the National Committee for Responsive Philanthropy. Despite the labor boycott and Devine's complaint that contributions had fallen off in several cities because of it, Bothwell said overall CFC donations were up by 7.5 percent last year, the largest increase since 1977.

And while proponents of restricting the CFC to traditional charities say it will result in a better managed fund-raising drive, opponents say the restriction will eliminate hundreds of charities that actively work to help the poor, minorities, women, children, Vietnam veterans and the environment.

Whatever the outcome of the charities debate--and Frank's subcommittee intends to hold more hearings once the new CFC regulations are made public--critics of the new order say it will hurt most those groups and services already affected by Reagan budget cuts.

The NAACP Legal Defense and Education Fund, which sued successfully to gain admittance to the campaign, has asked a federal judge to reopen the case in the face of the new executive order. Other advocacy groups, whose CFC contributions make up a healthy chunk of their budgets, also are threatening legal action if they are ousted from the charity drive.