The Reagan administration and a coalition of Senate supporters and critics tried yesterday to tighten the anti-discriminatory provisions of its tuition tax credit proposal in an effort to push the legislation through Congress before it adjourns.

But the package of amendments to be proposed today in the Senate Finance Committee by Chairman Robert J. Dole (R-Kan.) and Sens. Daniel Patrick Moynihan (D-N.Y.) and Bob Packwood (R-Ore.) failed to satisfy Sen. Bill Bradley (D-N.J.), chief critic of the measure's anti-bias provisions.

A spokesman for Bradley said he "does not oppose what the White House offers but thinks it is insufficient."

Bradley, a supporter of tuition tax credits, is to offer his own package of anti-discriminatory amendments today, and a congressional aide predicted enough committee votes.

Dole, Packwood and Moynihan met yesterday with Reagan and later told reporters in the White House driveway that Reagan had promised personally to fight for enactment of the tuition tax credit bill during this session of Congress. Moynihan said lobbying by Reagan was "essential" if the legislation is to be passed.

The three senators also described the new administration-backed amendments. They would require schools to publish a statement of nondiscrimination, would allow any person, personally affected or not, to file an anti-discrimination lawsuit, and would penalize any school that discriminated by denying it tax credits.

Bradley wants to give enforcement powers to the Internal Revenue Service and the Justice Department. The issue has been particularly sensitive to the Reagan administration since last January, when it reversed a longtime policy and said the IRS could not deny tax-exempt status to schools that discriminate.

Meanwhile, Clarence Pendleton Jr., chairman of the U.S. Civil Rights Commission, said Reagan had agreed to the idea of a black summit meeting at Camp David to hear minority groups' views on civil rights.

Pendleton made the statement in the wake of criticism from 33 members of the commission's state advisory committee who wanted to meet with the president and express their disapproval of administration civil rights policies.

On Monday, White House deputy press secretary Larry Speakes said the advisory committee had not requested a meeting with Reagan. Speakes corrected himself yesterday and said that the request had been received but that "our preference" was for the state committee to advise the commission and not the president directly.

Pendleton, seeking to quiet committee members' concern that he is "a mouthpiece" for the administration, said subsequently that a presidential policy statement was being drafted and that Reagan was amenable to the Camp David meeting if properly structured.

According to Pendleton, suggestions for the policy statement and the Camp David meeting were made to the president directly at a June 28 meeting attended by White House counselor Edwin Meese III and other top advisers.