NEW YORK — Joseph L. Birman, a physics professor who was honored for his humanitarian work with scientists facing repression in the former Soviet Union and elsewhere, helping scores of them to come to the United States, died on Oct. 1 in New Rochelle, N.Y. He was 89.

The cause was complications of cancer, his son Carl David Birman said.

Dr. Birman, a theoretical physicist at City College in New York whose specialty was condensed-matter theory, was widely known for his work with such organizations as the Committee of Concerned Scientists.

With the French-American theoretical physicist Pierre Hohenberg, Dr. Birman set up the committee’s Program for Refugee Scientists, which helped more than 100 émigrés restart their scientific careers in the United States in the 1990s.

In 2010, he was one of three recipients of the Andrei Sakharov Prize, given by the American Physical Society in recognition of outstanding leadership or achievements in upholding human rights. He was a member of the society’s committee on the international freedom of scientists.

Dr. Birman was known as a tenacious fighter.

“He would hector, debate, impress, push, cajole until every contrary sentiment and argument lay exhausted,’’ Irving A. Lerch, the American Physical Society’s former director for international affairs, wrote in a tribute. Dr. Birman, he added, had helped make his “the generation that put to rest — forever — whether or not scientists have the right, the obligation, to speak out.’’

As early as the 1970s, Dr. Birman helped organize joint symposiums between the United States and the Soviet Union in New York, Moscow, and St. Petersburg (then Leningrad). Jiufeng J. Tu, a City College colleague, said Dr. Birman and his co-organizers “would run the official meetings during the day and the unofficial refuseniks’ science seminar at someone’s apartment in the evening.’’

The refuseniks were Soviet citizens, many of them Jewish, who were refused permission to emigrate and dismissed from their jobs, leaving the scientists among them with no access to research institutions. There was a personal element to Dr. Birman’s interest: He was the grandson of Jewish immigrants from Russia.

In 2006, he received the Heinz R. Pagels Human Rights of Scientists Award from the New York Academy of Sciences, for which he was chairman of the Committee on the Human Rights of Scientists. The Pagels award is given for contributions toward advancing the human rights of scientists throughout the world.

Dr. Birman also worked with dissident Chinese scientists and, as he did with their Eastern European counterparts, helped them come to the United States and restart their careers. Dr. Tu recalled, “The word of mouth among Chinese scientists coming to the United States at that time was that their first contact had to be Professor Birman at C.C.N.Y.’’

A native of the Bronx, Joseph Leon Birman earned a bachelor’s degree from City College in 1947, a master’s from Columbia in 1950, and a doctorate from Columbia in 1952.

He began his career in the business world as a senior scientist at GTE Research Labs in New Jersey. But after a decade, he switched to academia, going to work for New York University in 1962. He became a physics professor there and remained until 1974, when he joined the faculty of City College.

At his death, he was a distinguished professor of physics there. An associate said that as recently as May he was talking eagerly about lectures he was preparing for the fall semester.

Most of Dr. Birman’s published quotations came from his scientific papers and were likely to be about subjects such as lattice dynamics or optical properties in fractional quantum hall systems. But during a brutal heat wave in July 1982, a reporter for The New York Times caught up with him in New Rochelle and asked him about the weather.

“Out here, there’s less of a feeling of being oppressed by other hot people,’’ Dr. Birman said. “Concrete sidewalks in the city absorb the heat and radiate it for a long time. Grass cools off more quickly.’’

He had already announced his scientific response to the situation: “I’m sitting quietly and trying not to think about it.’’