Clarence Thomas, chairman of the Equal Employment Opportunity Commission, said yesterday that the Reagan administration cannot effectively enforce anti-discrimination laws against private firms until it gets "its own house in order."

Thomas appeared on a National Urban League panel with William Bradford Reynolds, the assistant attorney general for civil rights, and Mary F. Berry, one of three members of the U.S. Civil Rights Commission recently replaced by President Reagan.

Thomas, who is black, offered little if any support for Reynolds' contention that the Justice Department is vigorously enforcing the nation's laws against racial discrimination.

"We cannot allow important matters of national policy to be reduced to simple matters of political posturing," Thomas said. "The issues we face are clearly too complex to be tossed around as oversimplified campaign slogans which inflame more than inform . . . . Our personal views on the laws we enforce are, at most, inconsequential. We have sworn to uphold the law."

Then Thomas added, to applause, "Furthermore, the executive branch in particular can exert leadership in this area by making sure its own house is in order. We cannot expect to be effective in enforcing the . . .laws in the private sector if we do not do all we can to comply with those laws ourselves."

Thomas' comments reflected similar recent complaints by women's groups, minorities and the Civil Rights Commission that the administration has failed to appoint enough women and minorities to top jobs and judgeships. His comments also appeared to support criticism that the Justice Department and other federal agencies do not enforce anti-discrimination laws--particularly on quotas and affirmative action, which are opposed by the president.

Berry, a black woman who along with a rabbi and a Hispanic woman was removed from the Civil Rights Commission in favor of three white men who share Reagan's opposition to busing and quotas, said that even when the administration does take legal action in support of blacks' civil rights it reaches agreements that rule out class-action remedies because they are contrary to the Republican Party's platform.

"The answer as to who is going to enforce the law . . . , " Berry said, "is the agencies responsible will enforce that part of the law if they like that part of the law . . . . If it's consistent with the Republican Party platform they'll enforce it."

Berry said all black Americans can do is "suffer, survive and hope the Justice Department does not enter cases."

Reynolds, who is white, cited statistics showing his office breaking records for action in support of enforcing civil rights and said Justice has been "neither timid nor selective" in attacking discrimination.

"We are not a special-interest law firm and we cannot tailor our legal interpretation or our enforcement policies to serve any particular group, whether its membership is defined by economic circumstance, political affiliation, race," Reynolds said.

"We cannot condemn practices of discrimination against black police officers in Nassau and Suffolk counties, N.Y., or Milwaukee, Wis., and ignore the claims of unlawful discrimination by Hispanics, females and white officers challenging a promotion quota that favors blacks."