The percentage of student aid flowing to minorities at public colleges and universities dropped sharply in the 1983-84 academic year as more white, older and self-supporting students used aid money to go to school, according to a report released yesterday.

The number of aid recipients dropped by 2.3 percent that year compared with two years earlier, according to "Student Aid and Public Higher Education," prepared by the American Association of State Colleges and Universities.

But the percentage of aid recipients who were minorities dropped more dramatically: 12.4 percent from the 1981-82 academic year.

The report also found that more aid recipients work while attending school -- suggesting that student aid has not kept pace with rising college costs.

Educators offered various explanations for the decline in the number of minorities receiving aid. They include a general decline in minority college enrollment, a perceived reluctance by minorities to assume massive debts as aid shifts from grants to repayable loans, and the possibility that news of pending aid cuts has discouraged some minorities from applying.

"This calls for someone or some organization to take a closer look," said Mary Margaret Walker, spokesman for the association.

The report comes amid an ongoing debate over the Reagan administration's proposed cuts in the Guaranteed Student Loan program and tough new eligibility standards for all types of federal aid.

The latest report follows a study by the association which found declining black and Hispanic enrollment in relation to the number of new college-eligible minorities.