The Carter administration claimed yesterday the nationwide shutdown of major trucking firms is causing little immediate economic disruption and indicated its anti-inflation guidelines are elastic enough to accommodate Teamster money demands.

In the administration's first official comment on the combined strike and lockout that began Sunday, Labor Secretary Ray Marshall said the government has no plans "at this point" to seek an injunction to force resumption of normal trucking operations.

He also released a Labor Department study that concludes that "it does not appear that a short (one-to two-weeks) strike will seriously impact on food supplies and other critical commodities."

Although auto industry layoffs are mounting and supply interruptions have been reported by other industries, the report said that no imminent shortages are expected in food, coal, petroleum, construction materials and medical supplies.

Meanwhile, chief federal mediator Wayne L. Horvitz announced that contract negotiations will resume tomorrow afternoon in the mediation service's offices here. The talks collapsed late Saturday when the old contract expired without a new agreement, prompting a selective strike by the Teamsters and a retaliatory "defensive shutdown" by most major trucking firms.

Marshall's news conference was devoted largely to a defense of the administration's guidelines program and a denial of widely published reports that the administration relaxed its 7 percent guideline for annual wage and benefit increases in order to keep the Teamsters from demolishing it with a guideline-busting settlement.

The administration's decision last week to exempt a 21-cent-an-hour cost-of-living increase from the guidelines was in line with his interpretation of the wage standard as a "flexible" guideline, Marshall said.

Marshall also argued that the industry's final bargaining offer, which chief industry negotiator J. Curtis Counts described as exceeding 30 percent over three years, was within the wage guideline of 7 percent a year or 22.5 percent compounded over three years.

The difference, Marshall indicated, is that the guidelines assume a 6 percent inflation rate for the purpose of calculating cost-of-living increases while Counts was assuming an 8.5 percent increase, roughly what is expected for the next 12 months.

"If it's 30 percent by the way whoever figures it and we figure it at 22 1/2 perrcent, it would be within the guidelines," said Marshall.

Asked if this meant the Teamsters could theoretically get a 10 percent annual increase if inflation runs around 9 percent, as some are predicting, Marshall said they could do so and still be within the guidelines because cost-of-living increases are counted at 6 percent no matter how high they go.

Disputing reporters' suggestions that the guidelines have been stretched to the point of collapse, Marshall said the program has been a "success" in keeping down wages, although prices have continued to rise.

As for the Teamster negotiations, he said he believed the union's demands, which reportedly included another 20-plus cents an hour in cost-of-living payments, could have been accommodated within the guidelines.

"From what I know, it was perfectly possible for settlement to be reached that would have been within the guidelines and satisfied the demands of both sides," he said.

Industry bargainers, rejected the union's demand, saying it would cause the contract to breach the guidelines.

Marshall's interpretation of the guidelines and their applicability to the Teamster talks appeared to be looser than that of government anti-inflation officials, and Marshall indicated he disagreed with some of their rhetoric as well.

Asked about presidential inflation adviser Alfred E. Kahn's threat to deregulate the trucking industry if the Teamsters broke the guidelines and his assertion that a high settlement would be an "act of aggression against the American people," Marshall said, "I would not have made those statements."

So far the trucking lockout, which the industry estimates as affecting 500 firms and roughly 235,000 of the 300,000 Teamsters covered by the master freight contract, has affected the auto industry most severely. Auto industry officials said 86,000 workers were laid off or put on short shifts yesterday and indicated the figure would grow to 107,000 today.