Transportation Secretary Drew Lewis said yesterday if necessary he is prepared to recommend limits on Japanese car imports as part of an auto industry recovery package, but only if concessions are made by labor and management.

At the same time, the White House asked Congress to postpone hearings on legislation to place quotas on Japanese imports until the administration's auto task force, which is headed by Lewis, has completed its report to President Reagan in mid-March. Hearings were scheduled to begin next Friday.

Pressure is building on Capitol Hill for some fast action to help the auto industry, congressional sources said, and some members of Congress aren't willing to wait a long time for the Reagan administration to act.

So far two bills limiting Japanese imports have been introduced, but U.S. Trade Representative William Brock said yesterday that "under any circumstances, negotiations are preferable to legislation."

Meanwhile, Lewis said during a press conference in Detroit that the level of Japanese auto imports is "unacceptable." But before the government can impose any import restrictions, labor and management must "bring something to the table." Lewis gave no specifics on how the government would restrict imports, but he suggested that wage, price and investment concessions from Detroit could be part of a package.

"I can say this unequivocally, that my position will be and has been that the present level of Japanese imports is unacceptable," Lewis told reporters. "I am also prepared, if necessary and if it appears reasonable, to recommend to the president some kind of import restraints."

Concessions from labor unions may be similar to those the United Auto Workers union made to help bolster Chrysler Corp. UAW President Douglas Fraser, after meeting with trade officials here last week, said that the union would be willing to help the industry get capital if the government came up with an appropriate aid package.

Administration sources said that the task force hasn't yet made any recommendations on help for the auto industry but that a package of regulatory, tax and import policy changes tied to concessions from management and labor is being studied.

Sources also said that Lewis didn't mean that import restraints would necessarily be part of such a package, but that limits weren't being ruled out, either.

Lewis characterized Reagan as a man of "basic principles, and free trade is one of them. But he has deep concern for the auto industry, and I'm confident we'll get a fair hearing."

Lewis, head of the administration's task force, was meeting in Detroit this week with auto executives, labor leaders and local government officials. He and trade representatives Brock yesterday asked Sen. John C. Danforth (R-Mo.) to postpone hearings on legislation that would limit for three years the number of Japanese autos sold here annually from 1.9 million last year to 1.6 million units. Danforth, chairman of the Senate Finance trade subcommittee, said he will hold off on the hearings.

Increasing the momentum on Capitol Hill for import restrictions, Reps. William Brodhead (D-Mich.) and Elwood Hills (R-Ind.) yesterday introduced legislation for stricter import quotas that would limit Japanese car sales between 1981 and 1983 to 1.2 million cars. During 1984 imports would be limited to 1.26 million autos, and in 1985 Japanese car sales would be allowed to grow 5 percent to 1.323 million, according to Ron Smith, Hillis' chief legislative assistant.