The presidents of American colleges have become so tied down and "weakened" by interest groups and regulations that few can provide strong leadership, according to a study panel headed by Clark Kerr, former president of the University of California.

After a 2 1/2-year study, the panel said yesterday that the growing troubles of their presidents have made colleges less dynamic and less able to plan their own futures, reacting instead to outside pressures while trying to postpone difficult decisions.

"This is not nostalgia for benevolent autocrats," Kerr said at a news conference yesterday at the Capital Hilton Hotel. "Some of the changes were inevitable and some of them are desirable, but it's our feeling that they've gone too far. . . . It's like Gulliver and the Lilliputians. . . . The whole position of president has become very constrained."

David Riesman, a Harvard University sociology professor who was senior consultant to Kerr's study, said the growing limits on the college president have made it difficult to attract and keep good people in the job.

The situation has been worsened, Riesman said, by "sunshine" laws and similar full-disclosure policies, which have led many public colleges and some private ones to publicize the names they are considering to fill vacancies. In addition to ruling out people with high-level jobs who do not want to undermine their current positions, Riesman said publicity also opens the way to "platitudinous campaigners who make speeches that are pleasing to everyone but turn out to be dreadful presidents."

The report, called "Presidents Make a Difference: Strengthening Leadership in Colleges and Universities," was issued by an 18-member commission, headed by Kerr and appointed by the Association of Governing Boards of Universities and Colleges. The project was financed by a $283,000 grant from the Carnegie Corporation.

The 102-page report also said:

*The average term of a college president has dropped to seven years with two years of effectiveness lost on the way in and out.

*College presidents have generally ceased to be leaders of public opinion. "They don't want to offend people," Riesman said.

*Trustees have become too involved in "administrative" issues such as appointments and admissions, rather than sticking to policy questions.

*Faculty union contracts have limited the authority of presidents and their ability to take initiatives.

*The spouses of presidents often are dissatisfied while the presidents themselves are often lonely.

Kerr said "courageous" presidents who seek needed changes frequently lose their jobs while those who avoid "run-ins with pressure groups" survive.

The study panel interviewed 400 current college presidents, 100 former presidents, 128 presidential spouses and 220 other people, including university trustees, faculty members and state officials.

Among them was Jay Carsey, former president of Charles County Community College in Maryland who disappeared in 1982, leaving his wife and his job of 17 years. Kerr said he interviewed Carsey for several hours but promised not to disclose his whereabouts.

In a speech to about 1,000 people at AGB's fall meeting, the Rev. Timothy Healy, president of Georgetown University, praised the study but said it may give too little attention to "the excitements and rewards of the president's job." Healy said the president's chief concern must be the "academic health of the institution."

"Restiveness, dissatisfaction, anger and frustration thrive in direct proportion to academic weakness," Healy declared, " and to intellectual incompetence . . . . "

Kerr, 73, headed two Carnegie Foundation study groups on higher education after he was fired as University of California president in 1967 shortly after Ronald Reagan became the state's governor.

The panel said it supported "the need for wide consultation and the approach of shared governance," but it concluded, in many institutions "the share of the president in governance is now too small."