The Carter administration, in a policy reversal, is no longer ruling out an "orderly marketing agreement" (OMA) that would limit the importation of steel. White House adviser Robert S. Strauss said yesterday.

Strauss, whose title is special trade representative, with the rank of ambassador, made the remark as Bethlehem Steel Corp., the nation's No. 2 producer, said it would lay off 2,500 salaried employees this month.

Since mid-year the steel industry, troubled by sluggish sales and falling profits, has laid off about 18,000 employees. About half worked for Bethlehem, primarily at mills in Johnstown, Pa., and Lackawanna. N.Y., the same cities that would be hit by the new payroll cuts. In Johnstown, the unemployment rate is reported to be 25 per cent.

Strauss earlier this year concluded orderly marketing agreements with Japan on color television sets and with South Korea and Taiwan on shoes, limiting the annual growth of their exprts here.

He said those OMAs, although highly criticized at the time - within the administration as well as outside - had "put down the fires of protectionism," and that retail TV set prices here had come down instead of increasing as critics had warned.

Now, he said, "we can't exclude anything" in relation to steel. He reported he is organizing an official advisory group on steel representing a cross-section of U.S. business, labor and political interests, and if they recommend OMAs, that device "will have to be considered."

Strauss said earlier in interviews and in congressional testimony that the OMA approach would not be used for steel. But yesterday, in backing away from that assurance, he said: "All bets are off in steel. But we hope to have a creative and innovative program."

President Carter announced Thursday a separate agency task force headed by Under Secretary of the Treasury Anthony Solomon to explore all of the steel industry's problems. Carter mentioned among other things, less efficient and less modern steel facilities in this country, and the difficulty the industry has had in adjusting to environmental restrictions.

Strauss estimated yesterday that only about 20 to 25 per cent of the industry's problems could be attributed to import competition. But he said that unless the government finds some short-term relief for the industry. Congress, "which is hearing from workers out of jobs, will take action. It doesn't take too much mail to bring legislative action, sometimes emotional."

Meanwhile, industry and union-spokesmen joined some bitter criticism of the administration.Edgar Speer, chairman of United States Steel Corp., the nation's leading producer, said that Carter had been "very poorly advised" to say that one of the industry's problems was its failure to modernize old facilities.

"This is completely untrue," Speer said at a Sharon, Pa., news conference. he reiterated the claim that the industry's main problem is "dumping" by foreign producers - sales here at prices lower than those quoted in their own domestic markets.

United Steelworkers of America Secretary Lynn Williams, according to the Associated Press, labeled Carter "callous" for failing to impose import restrictions. At a rally in Cleveland, Ohio's Republican Gov. James A. Rhodes joined Williams and other union officials, saying he favors limiting steel imports to 10 per cent to total U.S. steel sales - or about half of the current level of imports.

Strauss, just back from trade talks in Europe - where the steel industry also is under pressure because of falling demand - said he had met. This week with 20 senators from states where steel is a major employer, and had discussed their probelms at a White House session Thursday night.

"There is plenty of blame to go around, Strauss said. "I've told the industry they should look at the kind of tax relief [that mught be required] to get rid of obsolescence. . I don't think that raising prices in the face of import competition is the answer, but they disagree."