Alexandria officials, responding to a grievance filed by 25 black employes, promised yesterday to establish a new affirmative action policy that is intended to improve the chances for minorities to gain jobs and promotions in the city government.

City officials stopped short of acknowledging any specific wrongdoing, but Mayor James P. Moran Jr. said the city "wanted to work something out. There was some basis for their complaint."

By June 1, the Human Services Department, where the 25 workers are employed, will begin enforcing a new policy for promoting blacks. The provisions of that policy also will be included in a revised affirmative action program for all the city's 1,800 city employes, officials said.

In addition to altering the promotion policy, the Human Services Department will change its procedures for career development, job evaluations and training, said Gary C. Cyphers, assistant city manager and director of the agency.

"I believed that the department would be well advised to adopt many of the things they the employes were requesting," Cyphers said. He said his department has never had problems hiring blacks, but that there were valid concerns about promotions. About 40 percent of the city's 175 Human Services employes are black, he said.

"I'm really happy," said Paulette Jackson, a social worker who led the group that filed a racial discrimination complaint against the city in January. "We were concerned that blacks were not getting the promotions and transfers . . . . Blacks weren't even being informed of the positions available."

Cyphers insisted in his written response to the grievance that "the record is clear that there has been no discrimination in promotion." Of the 24 promotions in his department since 1982, he said 10 were given to blacks. Still, he said, some procedures were not sufficient and "employes would be better served by a more specific plan."

Michael T. Leibig, the Washington lawyer representing the workers, said he disagreed with some of Cyphers' assertions that the department "met the spirit or intent" of the 1980 citywide affirmative action program. Leibig said that because the workers had been "treated with respect and answered with reason" they accepted they city's offer to revise the affirmative action plan.

To update the six-year-old affirmative action program, City Manager Vola Lawson has asked Patricia Toste, the director of the Office on Women, to begin developing a proposal to present later this year to the City Council.

"I was really pleased with this," said Lawson, who said the city is planning outreach programs in the community to keep minorities and women informed of opportunities for career advancement with the city.