A major New York City investment banking firm donated $100,000 to Georgetown University yesterday after learning that Georgetown had returned a $600,000 gift plus interest to the government of Libya.

"We read the story in the newspapers, and we were very impressed by their stand," said Alan C. Greenberg, senior managing partner of Bear, Stearns & Co."We admire them, and this is our little way of saying thank you."

Greenberg said he telephoned the Rev. Timothy S. Healy, Georgetown's president, to tell him of the firm's gift and to praise Georgetown for its "courageous stance and uncompromising standards." He said he told Healy "that he could do whatever he wants to with (the contribution)."

On Monday Healy personally delivered a check for $641,721, including the interest, to the Libyan Embassy. He said Georgetown was returning the money, which had been given for a professorship of Arab studies, because it did not want to have "its name associated" with a government that supports terrorism.

Healy said yesterday he was "at once surprised and grateful" for the Bear, Stearns gift. "This is the first time that I've ever seen a gift before I saw the giver," Healy said. He said the money would be used for undergraduate student aid.