Gunmen kidnaped a U.S. professor of the American University of Beirut yesterday in what may have been an attempt to abduct Dr. Calvin Plimpton, the school's president.

Scottish-born Thomas Sutherland, 54, an American citizen and dean of the agriculture and food sciences faculty, was ambushed on his way from the airport by at least two carloads of militiamen, university and security officials disclosed today. He became the school's fourth staff member to be abducted and the seventh American missing from the Moslem-controlled western sector of the Lebanese capital.

Sutherland and Plimpton were expected to return from the United States via London over the weekend, but the university president called and canceled his scheduled arrival at the last minute, university officials said. Plimpton is the most prominent American citizen residing on the campus in the western half of Beirut.

While Sutherland was being driven from the airport in what was reported to be Plimpton's car, gunmen shot at the tires of the auto, bringing it to a halt. He was forced to go with them, but his driver was freed. No group has claimed responsibility.

University spokesman Radwan Mawlawi said Sutherland, of Fort Collins, Colo., had turned down a security escort. Describing the teacher, originally from Glasgow, as "a true friend of the Arabs," Mawlawi said he had gone to the United States for a conference and to see his family.

On May 28, another senior university official, hospital director David Jacobsen of Huntington Beach, Cal., was abducted while on his way to work.

Islamic Jihad, a front apparently including a disparate set of underground groups bent on driving out foreigners, and Americans in particular, said it was holding Jacobsen. It released a snapshot of him one day after he was captured.

As the price of freeing five Americans and two Frenchmen thought to be held by Islamic Jihad, the group has demanded release of 17 persons jailed in Kuwait for the bombing of U.S. and French embassies there in 1983.

Denis Hill, a British professor at the university, was found shot to death south of Beirut one day after he was kidnaped on May 27. Although anonymous callers claimed Islamic Jihad had killed him and detained two missing French journalists, a typewritten statement with the Islamic Jihad insignia denied responsibility for Hill's shooting.

University librarian Peter Kilburn, 63, left work on Dec. 3, 1984, and has not been seen since. In January of last year, gunmen assassinated the school's acting president, Malcolm Kerr, as he left an elevator for his office. Islamic Jihad claimed responsibility.

The 118-year-old academic center has produced physicians, engineers, scientists and historians to work in the region. Its survival is at stake because of a financial deficit of $15 million that is projected to shoot up to $19 million in 1986 and $30 million the year after.

This year's budget is $85 million. The U.S. government has been the main financial backer. Plimpton, 66, a Harvard-educated physician, came out of retirement last year to assume stewardship of the university despite the growing risk for Americans in Beirut.

University officials fear that stepped-up attacks targeting American and non-American staff will jeopardize the university's chances of obtaining financial aid.