The Carter administration announced plans yesterday to step up its new anti-inflation program - both by intensifying its jawboning of business and labor and by tightening the reins on government spending and regulatory activities.

In a meeting with reporters, Robert Strauss, President Carter's new anti-inflation czar, said the moves were designed to show that the wage-price program now has more "credibility" - in hopes of persuading labor leaders to go along with the plan.

Strauss also said he expects to see "positive results" soon in the administration's campaign to slow postal workers' pay increases. At the same time, however, he confirmed earlier reports that the White House is losing a similar bid to moderate railroad workers' pay boosts.

The session was one of a series of such meetings called recently at the urging of Gerald Rafshoon, President Carter's new public relations adviser. Officials said later the briefings were designed to get across the message that the administration has an orderly economic strategy.

Strauss listed three major areas in which the White House is stepping up its anti-inflation effort:

Increased contacts with business and labor leaders to seek pledges of cooperation, and more public jawboning by top officials - including some regional appearances by Cabinet officers to plug the wage-price strategy.

Intensified efforts within the administration to crack down on government actions that contribute to inflation. The White House already has set up a Cabinet level anti-inflation task force, and officials new have a special review group to consider regulatory actions.

Stepped-up White House efforts to trim the projected federal budget deficits for this year and fiscal 1979 and 1980 - even at the expense of part of the president's already-scaled-down tax cut plan. Carter's threat on Wednesday to veto the public works bill was an example.

Strauss also made a point of asserting that Carter himself now is more committed to fighting inflation. "I don't think there can be any doubt in anyone's mind that President Carter is deadly serious about inflation," Strauss said.

The anti-inflation chief also defended the administration against charges that the program had not yet achieved concrete results, "Maybe we didn't hit a home run," he said, "but I know we did make visible progress." He later predicted more "visible progress" by mid-autumn.

Strauss declined to spell out any goals against which the administration could measure progress on the inflation front, buy Barry Bosworth, director of the Counci on Wage and Price Stability, suggested that a decline in the hourly earnings index would be a good yardstick.

Bossworth forecast that there almost certainly will be "some wage acceleration" in the second half of 1978, if only because of cost-of-living increases stemming from the price surge earlier this year. But "you have to see a leveling off" if the program is successful, he said.

Strauss also pointed to the recent White House compromise over Labor Department standards for regulating cotton-dust hazards as a victory in principle for the administration's inflation fighters. He said reports that they had caved in were highly exaggerated.