Sen. Gordon J. Humphrey (R-N.H.) called yesterday for an investigation by the Senate Judiciary Committee to determine whether a black law professor was intimidated from testifying last month in favor of Judge Robert H. Bork's nomination to the Supreme Court.

The professor, John T. Baker of Indiana University Law School, decided not to testify as scheduled Sept. 28 after a phone call from Linda Greene, a lawyer appointed to the Senate Judiciary Committee staff last year by Sen. Howard M. Metzenbaum (D-Ohio). The incident, in which she warned Baker that his appearance might turn into a painful ordeal, was reported yesterday in The New York Times.

Greene said yesterday that she made the call to advise a friend, not as any attempt at intimidation, and Metzenbaum said Humphrey's statement merely shows that the pro-Bork forces are desperate as Bork's nomination awaits a final vote on the Senate floor.

Baker, who resigned last year as dean of Howard University Law School after expressing dissatisfaction with educational standards, did not return phone calls yesterday. But in a letter last week to Metzenbaum, he took "complete responsibility for my decision" not to testify. He said he took the step after conferring with "people supporting and opposing" the Bork nomination "concerning both the risks and benefits of testifying."

Humphrey, a Judiciary Committee member, denounced Greene's action as "highly offensive . . . irregular and perhaps illegal . . . . Inasmuch as a black was intimidated, it smacks of Ku Klux Klan tactics." Greene is also black.

Metzenbaum, a leading opponent of the Bork nomination, responded that "this shows how desperate the White House has become . . . . The issue is Judge Bork's views and record, not a private conversation between two longtime friends."

Greene, a counsel for the Senate Judiciary antitrust subcommittee, of which Metzenbaum is chairman, said yesterday that the call was her idea and that Metzenbaum did not sanction it or know of it.

"I did it out of sisterly love for a fellow black professor," said Greene, who has taught law at the University of Oregon, Harvard and Georgetown.

Her immediate superior, Eddie Correia, chief counsel of the subcommittee, said in a separate interview that Metzenbaum had no plans to put tough questions to Baker or even to attend the Sept. 28 hearing at which Baker was to testify.

Greene called Baker, the only black law professor scheduled to testify on Bork's behalf, on Sept. 27 and, according to the Times account, asked him "if he was prepared to answer the tough questioning he was going to get" about the controversy concerning his resignation from Howard and about issues of constitutional law that he might not be familiar with.

"I told him, 'If you come here, you become the issue,' " the Times quoted her as saying.

"I don't remember saying that," Greene said last night. "I never suggested anything about Howard would come up in the questioning. I thought it might come up in the press . . . . I think what I intended to say was that his background and expertise would become the issue."

Baker resigned from Howard last May in a dispute over whether a group of law school students should have been permitted to graduate despite a law faculty decision that they were ineligible. Baker had protested in a memo that Howard law students were "not being properly educated . . . research and scholarship are practically nonexistent." However, Howard President James E. Cheek said at the time that he requested Baker's resignation because of "incompetence" and "insubordination."

After the phone call from Greene and conversations with others, Baker decided not to testify. "I just couldn't take the heat," he was quoted as having told a friend from the University of Oregon.

After talking again with Greene last week, however, Baker told the Times that "I was not intimidated by Linda Greene or anyone else."

Humphrey said he would write Senate Judiciary Committee Chairman Joseph R. Biden Jr. (D-Del.) and ranking Republican Strom Thurmond (R-S.C.) today to ask for an immediate inquiry. Humphrey said he wants to determine "whether the aide was acting with authorization or encouragement from her superiors."

"The aide claims she did it out of friendliness, but to me that doesn't wash," Humphrey said in a telephone interview. "From the details, it looks like another element in this campaign of fear-mongering in which Bork opponents have engaged for several weeks."

Jerry Berman, chief legislative counsel of the American Civil Liberties Union, which opposes Bork's nomination, charged that Humphrey's statements were a case of "the pot calling the kettle black."

"We {at the ACLU} made the decision not to testify because we had it on good authority -- from Republican minority staffers whom I will not name -- that when we got up there, they were going to try to make us the issue," Berman said in a telephone interview. "We made the decision not because we couldn't take the heat, but because we didn't want to play into that strategy."