Action taken this week by the D.C. City Council threatens to cut as many as 2,539 jobs from Mayor Marion Barry's proposed summer employment program for youth, a mayoral aide said yesterday.

Acting on a proposal by council member Willie J. Hardy (D-Ward 7), the council voted to shift $1.4 million in funds proposed by the mayor for youth jobs to create instead 300 year round jobs for 500 persons aged 22 or more.

The money was part of $8.5 million in District of Columbia funds the mayor proposed to spend to hire 11,285 youth, aged 14 to 21, for the summer. These would be in addition to 13,500 summer youth jobs to be provided in the city with federal funds.

Audrey Rowe, the mayor's special assistant for youth affairs, said the council's shift-depending upon how it is interpreted-would trim youth jobs by at least 1,400 and perhaps by as many as 2,539.

The relatively large loss woul result, she said, from the fact that the youth would work 25 hours a week only until the end of the school vacation, while the 500 older jobholders would work 40 hours and remain on the payrool indefinitely.

Rowe said, however, that the cut in youth jobs would not create a crisis, since she expects them to be made up through increased employment by the city's private business community.

She also said she expected other jobs to be created by District agencies and paid from their normal operating funds. School Superintendent Vincent E. Reed told the cabinet that the school system plans to hire about 2,500 seniors for summer jobs-about 150 from each high school.

If the council position is carried over into the summer of 1980, Rowe said, about 4,000 youth jobs would be eliminated.

Barry told a meeting of his cabinet yesterday that he expects to sign the budget bill in which the council made the change in his program, and to reach some kind of "accommodation" with the council.

The mayor also said that, partly in response to Rep. Charles Wilson (D-Texas), he had decided to pay youths aged 14 and 15 a wage of $2.65 an hour-35 cents below the federal minimum wage. Those 16 and older would earn the $2.90 federal minimum.

Wilson, chairman of the House D.C. Appropriations Subcommittee, warned during a recent hearing on the city budget that he would cut Barry's jobs program if the mayor insisted on paying the youngest workers $2.90 an hour.

The council-passed budget bill, containing authority to spend $76.6 million in additional funds during the 1979 fiscal year, must be enacted by Congress.

Barry's job program would carry out a campaign promise to reduce joblessness among youth. According to official figures cited by the mayor, half the city's black youth were unable to get jobs last year.

The mayor told his cabinet that "we are going to insist that the young people work," and that employing agencies should "not just put them in a corner" to do nothing.

Hardy, chairman of the council's Housing and Economic Development Committe, said she supported the youth jobs program, but felt strongly that the 500 jobs should be set aside for somewhat older workers-many with family responsibilities-who have been unable to find work.