The District of Columbia should lower the minimum wage for teen-agers to $2.50 an hour if the federal government enacts the Reagan administration's controversial subminimum wage proposal, Mayor Marion Barry said in a television interview to be broadcast tomorrow.

"We ought to be included. We ought to be included, of course," Barry said regarding the proposed federal minimum wage, which would be lowered from $3.35 to $2.50 per hour between May 1 and Sept. 30 for workers between the ages of 16 and 19.

Barry, chairman of the National Conference of Black Mayors, said: "We have no choice except to try it. When you have 40 to 50 to 65 percent unemployment among our young people in some of our cities, we would like to have something different, but it's not there. And it's better to have people working than standing on the corner or using drugs or going to jail."

He made his remarks on "It's Your Business," a broadcast produced and sponsored by the U.S. Chamber of Commerce, which backs the subminimum wage bill. The show airs at 12:30 p.m. Sunday on WJLA-TV, Channel 7.

The federal minimum wage does not apply in the District and 10 states, including Maryland, that already have higher minimums. If the Reagan administration is successful in passing its "Youth Employment Opportunity Wage," the lowered minimum would not apply in these 11 jurisdictions unless local laws are changed.

Under federal law, the federal minimum wage does not apply in states that have higher minimums. If the $2.50 minimum were enacted, it would be fully effective in only nine states that have no state minimums, and it would be "partially" effective in 31 states, including Virginia.

The administration, citing a 40 percent-plus unemployment rate among black teen-agers, has touted the law as a major weapon to combat joblessness because it would induce businesses to create new jobs. The Department of Labor estimates that up to 400,000 temporary jobs would be created, an estimate critics dispute.

Critics say the lowered wage would induce employers to fire or avoid hiring adults, and a dual pay system based on age is unfair to younger workers. Labor unions and some civil rights groups oppose the measure, and were successful in blocking it during Reagan's first term.

The black mayors' group is among dozens of organizations that have endorsed the concept.

Barry, when asked why the mayor's group had "broken ranks with other black leadership" on the issue, said that other job-creating tactics often have failed and the three-year "experiment" with the lowered wage is worth a try.

"We want to see if it works," he said. "I think it will."