Stressing Japan's new role as an economic leader, Japanese Prime Minister Zenko Suzuki said yesterday that he expects no concessions from the United States in return for voluntarily limiting exports of Japanese cars here.

When U.S. Trade Representative William E. Brock visited Japan last week to consult him on the export limits, "There was no discussion of a quid pro quo, Suzuki said during a nearly-two-hour breakfast meeting with Washington Post editors and reporters.The prime minister spoke through an interpreter.

He also surprised some U.S. government officials by saying that he wants to work with the United States "for the mutual accelerated reduction" of tariffs on semiconductors, an industry that American businessmen expect to be the next trade battleground following the auto problem. "This is something we'd like to promote in principle," Suzuki said.

Semiconductors, which act like tiny brains in computers, are an integral part of the burgeoning and highly competitive high-technology business. Surpluses and deficits in that trade have been seesawing between the two countries. Last year Japan had the trade surplus.

When Brock discussed the multi-million-dollar trade in semiconductors between the two countries in Tokyo last week, Japanese government officials said they had made no decision on accelerating tariff reductions, a U.S. official said. The two countries previously had agreed to reduce both the 5.6 percent U.S. tariff and 10.1 percent Japanese tariff to 4.2 percent by 1987. But U.S. government officials pressed for reductions by next year, the official said.

Suzuki also said that internal financial problems are a high priority and that reducing the country's indebtedness "is the political issue on which I'm staking my whole political career."

The prime minister explained Japan's position in the auto discussions and, in a turnabout of history, how Japan decided it had a duty to help the disgtraught U.A. automakers.

The Japanese school of thought was that Detroit made its own problems by not reacting swiftly enough to higher gasoline prices by producing its own fuel-efficient cars.The public perception in Japan was "don't blame me," Suzuki said.

Despite harsh public criticism toward his government for limiting exports, "I made the decision because in the long run the decision would be in the best interests of" Japanese-U.S. relations, Suzuki said.

Meanwhile, the Justice Department said yesterday that Japan's voluntary-restraint plan does not violate U.S. antitrust law.