Randolph W. Bromery, the man who was selected last week to be the first president of the University of the District of Columbia, said yesterday that he will not take the job.

Bromery notified the university trustees of his decision by phone yesterday afternoon, saying that previous commitments at the University of Massachusetts -- where he is the chancellor for the Amherst campus -- led to his decision.

"It was the most difficult decision I've had to make in my 30 years as an educator," Bromery said. "But we are in the process of developing a longrange plan which has created a lot of anxiety on our campus. I couldn't walk away at this time."

"I told the (University of D.C.) trustees last Wednesday that my inclination was to decline their offer," he added. "I told the board I would think about it over the weekend and give them my final word today."

Bromery's final word was that he would remain at the University of Massachusetts where he has been the acting president of the state's university system since the resignation Saturday of the former president, Robert Wood.

"We are very disappointed by Dr. Bromery's decision to decline our offer, but we are not distraught," said Ronald Brown, chairman of the trustees of the University of the District of Columbia.

Brown said the trustees will not mount a new search for a university president in which "talented educators" around the country will be contacted about the job.

Earlier this year the trustees narrowed their selection of candidates for the job to four men picked from a field of 141 applicants nationwide.

The four finalists included Bromery, Walter C. Daniels, vice chancellor of the University of Missouri at Columbia, Herman R. Branson, the president of Lincoln University, West Chester, Pa., and Cleveland Dennard, former president of Washington Technical Institute, one of the three schools being merged to form the University of D.C. on Aug. 1. The other two schools are Federal City College and D.C. Teachers College.

Dr. Dennard, who had been the favorite candidate for the job among some trustees, students and faculty, resigned his post at WTI last Friday after it was announced that Bromery had been selected by the board of trustees as the president of the city's new public university.

Marjorie Parker, a board member, said she was "quite disappointed" that Bromery had turned down the job as university president. She said she is certain that some people would work to seek new board consideration of Dennard.

Asked if members of the board would want to reconsider Dennard, Mrs. Parker said: "I would think so . . . I wouldn't be surprised." Dennard himself said he had no comment on the situation.

City Councilman William Spaulding, acting head of the Council's education committee, described the trustees' present situation as "a real mess." He said he plans to call Brown to learn what the real problems are.

The University of D.C. trustees met last Monday and voted to extend the offer of the presidency to Bromery. The offer was made officially on Tuesday. The selection of Bromery to be president was thought to have resolved a lengthy and controversial search for a university administrator who would provide a balanced emphasis between vocational education and liberal arts.

The board's renewed search for a university president appears certain to rekindle the controversy over whether Dennard should be president of the new school.

Dennard had been president of WTI since it opened in 1968. Regarded as a forceful and able administrator, he shaped the academic program of the school and was a major force behind the development of the school's new $100 million campus at Connecticut Avenue and Van Ness Street NW.