Labor Secretary William E. Brock, breaking with the administration's civil rights policies, told the NAACP today that the nation will need affirmative-action programs "for a considerable period of time into the future."

Speaking at a news conference after addressing the group's annual convention, Brock refused to criticize directly the Justice Department's recent request to 51 jurisdictions that they consider revising affirmative-action programs.

He set down an argument for continuing affirmative action and said he does "intend to enforce the civil rights and affirmative-action laws as the laws were written and intended."

As labor secretary, Brock oversees federal contract-compliance programs to ascertain nondiscrimination and affirmative action in employment by government contractors.

Brock also offered little support for William Bradford Reynolds, head of the Justice Department's Civil Rights Division, whose nomination for the department's No. 3 job is stalled in a Senate committee.

"Never ask an administration to admit it made a mistake," he said when asked whether he supports Reynolds. "The nomination is being thoroughly challenged in the Senate. We'll see how it goes."

He added that, although a president sets national policies for the administration, President Reagan's political appointees have a responsibility for a "strong and effective enforcement of the civil rights laws."

Brock did not specifically endorse quotas as affirmative-action tools but said this most controversial form of affirmative action should not distract from the need for future affirmative-action plans.

"I think this country is going to have some form of affirmative action for a considerable period of time into the future," he said. "There is a distinction which you can make between absolute numbers and quotas and so-called goals approaches.

"But we as a country have lived for 200 years with a major part of our population in remarkable disadvantage," he continued. "And it takes some time to recover from that. Maybe we the generation of white Americans were not here then. But that does not change the obligation we have as citizens to respond to that situation . . . ."

Administration officials generally have adopted, as a policy goal, seeking "a color-blind society" in which no preferential treatment is given to minorities or women and no timetables, hiring goals or quotas used in affirmative-action plans. The administration would limit affirmative action to recruiting qualified blacks and women to apply for jobs.

Brock, who succeeded Raymond J. Donovan as labor secretary two months ago, defended Reagan against criticism from NAACP Executive Director Benjamin L. Hooks and other convention speakers. He said his first orders from Reagan were to deal with the 43 percent rate of unemployment among black teen-agers.

Although he and the NAACP may differ on "tactics," Brock said, he believes that the two have similar objectives.

He said he came to the convention to explain the administration's position that "a healthy economy, an improving economy . . . create a general climate in which people, particularly the disadvantaged, can make more progress."

Later, he added: "I don't think there is anyone who honestly believes that Ronald Reagan doesn't want the maximum opportunity for everyone in this country . . . ."

Brock dismissed sharp exchanges between the administration and civil-rights leaders as "bricks over the backyard fence" and said "sharp political lines" drawn in the 1984 presidential race made communications between the president and blacks very difficult.