The Reagan administration yesterday abandoned a 15-month effort to weaken a set of federal civil rights regulations that forbid state and local governments, universities and a wide variety of other recipients of federal financial aid from discriminating against the disabled.

The decision, revealed jointly by William Bradford Reynolds, assistant attorney general for civil rights, and C. Boyden Gray, counsel to Vice President Bush's Task Force on Regulatory Relief, marked an important victory for advocates who had fought the suggested revisions.

In a letter sent yesterday to Evan Kemp Jr., executive director of the Disability Rights Center Inc., Bush said, "A full evaluation of all the information brought to bear on this subject prompted the conclusion that extensive change of the existing 504 coordination regulations was not required, and that with respect to those few areas where clarification might be desirable, the courts are currently providing useful guidance and can be expected to do so in the future."

In an interview yesterday, Reynolds also said the administration was scrapping a related effort to limit the scope of civil rights rules affecting not only the disabled but blacks, Hispanics and women.

Under an executive order issued in the waning days of the Carter administration the Justice Department was given overall authority to write guidelines bringing order and uniformity to the multiplicity of agency regulations issued under various antidiscrimination laws.

Asked if he was abandoning the effort to change both the rules covering discrimination against the handicapped (known as sub-part B of the Justice Department's coordination guidelines) and the rules defining the scope of other civil rights laws (sub-part A), Reynolds replied, "Yes, I think that's right."

Asked if the existing broad civil rights rules covering recipients of federal aid would remain the status quo, he responded, "Yes, to the extent that anything remains status quo."

Earlier drafts of the coordination guidelines--never published but widely circulated--narrowed the definition of "federal financial aid recipient," restricted the government's authority to make discrimination complaints against such institutions and gave the federal government authority to delegate enforcement to the states.

All these suggestions met with strong opposition from such groups as the Leadership Conference on Civil Rights, the National Women's Law Center and the Center for Law and Social Policy.

Yesterday, spokesmen for these groups expressed guarded optimisim about the new developments.

"We're thrilled the administration has harkened to the cries of the civil rights advocates," said Barbara M. Milstein of the Center for Law and Scoial Policy. "But we're still very wary of what they will do in the courts."

Yesterday's decison apparently was made with an eye to pending federal court cases dealing with some of these issues. Some of the cases may produce the same results the administration had sought, while relieving it of direct responsibility for trimming civil rights rules.

In addition, since last summer, when a massive outcry by handicapped rights advocates forced the Department of Education to withdraw proposed changes in controversial department rules on the rights of disabled children, administration officials have been very sensitive to the potential political liability of restricting the current rules on handicapped rights.