Asserting that the $2.90 hourly minimum wage is too much to pay teenagers, the new chairman of the House D.C. appropriations subcommittee warned yesterday that Mayor Marion Barry's ambitious summer jobs program faces a probable cutback by Congress.

"It is absurd to pay kids under 18 [almost] $3 an hour -- a kid 16 years old is not worth the same wage as a man over 25," Rep. Charles Wilson (D-Texas) declared after a city budget hearing.

During the hearing, Wilson urged Matthew F. Shannon, acting director of the D.C. Department of Labor, to find a way to pay younger workers a lower wage.

Shannon said later that there is some sentiment on the D.C. City Council for a lower youth wage, and Barry may formally propose it "at an appropriate time."

Paying lower wages to young workers is strenuously opposed by organized labor, whose leaders believe some employers will hire them cheaply rather than paying for the higher skills of older workers.

Barry has proposed spending $11 million to create 13,285 summer jobs for young people. Of these, 11,285 would be nine-week jobs paying the federal minimum wage of $2.90 for youths 14 to 21 years old.

Unemployment at the lower range of this age group has reached crisis proportions, according to the Urban League and other groups concerned with city problems. Officially, the jobless rate in recent summers has topped 40 percent. Unofficially, it is said to be much higher.

An expanded summer jobs program was among Barry's campaign promises last year.

The mayor's spending request, part of a supplemental budget proposed for the current 1979 fiscal year, will be considered by Wilson's subcommittee if and when it is approved by the D.C. City Council, which is now considering it.

The program would be largely financed out of a requested $65-million increase in the federal government's annual payment to the City -- a point noted by Wilson in discussing the possible cutback.

Even if a lower wage could be paid, Wilson told reporters, "I doubt seriously if we would fund at the level the mayor is talking about, and I doubt the mayor thinks so."

In another District financial development, John A. Wilson (D-Ward 2), who recently succeeded Barry as chairman of the City Council's Finance and Revenue Committee, warned that the city faces a dangerously widening gap between its spending and its revenues in the next few years.

He urged the council to "exercise great restraint" in approving the supplemental budget requests from the mayor. Wherever possible, he said, city departments should "absorb costs from within by cutting back on lower priority programs."

Jacqueline Helm, staff director of the Finance and Revenue Committee, said council member Wilson's review of city finances has led him to sidetrack his proposal to rebate part of a $38 million cash balance at the end of the 1978 fiscal year to city taxpayers. "We do not have (that money) left over after paying all our bills," Wilson said.

Barry has proposed to use most of that money to finance programs in the 1980 fiscal year.

Unless Congress raises the federal payment above the $300 million a year now authorized by law, the council member said the city will have a gap between income and outgo of $102 million in 1981, $145 million in 1982, $201 million in 1983 and $252 million in 1984.