Some major U.S. firms requested by President Carter to withdraw voluntarily their participation in the Moscow Olympics have asked the government to make the pullout mandatory so that they might be protected from legal action by the Soviets.

Commerce Secretary Philip M. Klutznick, responding to questions from reporters at a breakfast meeting yesterday said: "There are certain companies that have outstanding contracts that could be seriously damaged" by a voluntary pullout of Olympic participation. Klutznick said that "substantial sums" of money were involved, but did not elaborate on how much or what companies are involved.

Making the withdrawal mandatory might relieve the companies of some responsibility for breaking any contracts they might have had with the Soviets. It could also protect the business integrity of future trade relations between those companies and the Soviets or other countries, another Commerce Department official said.

Some of the companies have complained that the Carter administration's action makes them appear to be unreliable trading partners. Honoring contractural commitments is an integral part of future dealings, the companies said.

Klutznick said, in response to a question, that he has not heard that business people fear the president will later change his mind, and remove the export controls and the Olympic withdrawal request he introduced as a result of the Soviet invasion of Afghanistan last December.

Those controls include tighter restrictions on the export of grain, high technology and technical know-how to the Soviets.

Carter earlier this month asked all U.S. companies to withdraw voluntarily the export of such products as pole vault pits, scoring devices and even baggage X-ray equipment to the games. Such a move would affect between $15 million and $20 million in merchandise.

Commerce officials yesterday said they had not determined whether any of the companies continued to send Olympic-related goods to the Soviets, but that none had so far been threatened with action by the Soviets if they did not live up to their contracts.

The Commerce Department is still contemplating whether to make the voluntary withdrawal mandatory and how it could be done, a Commerce spokesman said yesterday.

Klutznick also said the grain embargo is having its expected effect, although "there is some seepage undoubtedly." The government is having "a measure of success" in gaining allies to go along with the grain and high technology embargos, Klutznick said, adding "I think we have been substantially successful."

Klutznick said he has noticed a "good attitude from U.S. companies" toward complying with the embargoes and "with one or two exceptions, those companies called and volunteered" their compliance.

In another area, Klutznick said that administration officials decided to suspend the steel trigger price last week partly as an anti-inflation measure. The steel trigger price is an import price monitoring system set up about two years ago to determine whether foreign countries were selling steel products here at prices below their fair values.

The system establishes a minimum price at which steel can fairly be imported without injuring the domestic market. It was suspended after U.S. Steel Corp. filed dumping suits against seven European countries.

"The economists felt that taking any action other than what we took would be inflationary," Klutznick said. Commerce officials are still studying the effect of the suspension on European Economic Community countries, Klutznick said.