Commerce Secretary Malcolm Baldrige said yesterday the Japanese have taken a "real risk" of trade retaliation by refusing to extend limits on auto exports to the United States for a fourth year.

He told reporters at a breakfast meeting that the announcement made Thursday in Tokyo by Minister of International Trade and Industries Sosuke Uno harms efforts to ease trade tensions between the United States and its major Pacific ally and strengthens protectionist sentiments in this country.

The announcement came as a surprise to Baldrige, one of the administration's top trade officials, who visited Japan recently.

In another unexpected development, members of a high-level Japanese agricultural trade delegation reportedly surprised Americans with their sharp manner during a visit here this week. Sen. Edward Zorinsky (D-Neb.) became so annoyed that he walked out of a meeting with members of the Japanese parliament who were part of the delegation.

Baldrige said some change in the Japanese stance still is possible before the third year of restraints on shipments of Japanese autos to the United States ends on April 1, 1984. As another possibility, however, he said the Japanese may have wanted to make the announcement now to get the debate over before next year's American political campaign.

Some Washington trade experts have speculated that Uno's announcement was merely the first move in a Japanese effort to set new shipment limits substantially higher than the current limit. Others suggested that the head of MITI may have wanted to trigger the protectionist reaction that the announcement received on Capitol Hill as part of a campaign to convince Japanese automakers that a fourth year of restraints is necessary to prevent harsher measures by the Congress.

The Japanese automakers are concerned that the restraints are preventing them from capturing a larger share of the U.S. car market, which has just begun growing after three years of stagnation.

In April 1981, Japan agreed to hold auto shipments to the United States to 1.68 million units for that year, with an increase in 1982 if overall U.S. sales rose, which they did not.

The Japanese agreed in February to extend the restraints for a third year, but were noncommittal on a request by U.S. Trade Representative William E. Brock for a fourth year of limits, beginning next April.

"I think the Japanese are taking some real risks when they say they are not even going to negotiate for a fourth year," said Baldrige. "They are well aware of that. I am not sure what their reasons were in coming out like that. None of us are."

He said the Tokyo announcement increases the chances for passage of labor-supported local-content legislation requiring that an increasing percentage of the best-selling brands of imported cars--all Japanese--be made by American workers using U.S. parts.

"I still don't think it will pass, but this increases its chances," added Baldrige, the Reagan administration's point man in opposing the legislation.

Despite his dismay over the Japanese announcement, he cautioned against the growing sentiment on Capitol Hill to hit back.

"If we get exasperated at one incident or another and say we will lead the charge toward protectionism, we endanger the jobs of 20 percent of America's industrial workers and 40 percent of its farmers who depend on exports," Baldrige said.

On Capitol Hill, Sen. Robert Dole (R-Kan.), chairman of the Finance Committee, criticized the Japanese announcement and said it goes against promises by the government of Prime Minister Nakasone to cooperate with the United States on trade problems. He said Congress may take "remedial steps" if Japanese exports threaten the U.S. auto industry's recovery.

The Uno announcement "must call into question Japan's commitment to responsible participation in world trade," Dole said.