Japanese auto makers have taken a tough position opposing any reductions in exports to the United States, industry sources said today.

Industry leaders agreed at a meeting yesterday that the most they should do is to hold exports to last year's level, these sources said, confirming Japanese press accounts of their meeting.

The meeting had been hurriedly arranged for top officials of all seven Japanese auto companies as the industry and government approached a showdown on what has become the major controversy in U.s.-Japanese relations. s

The auto makers are sharply at odds with the Ministry of International Trade and Industry, which favors some reduction in exports. Its minister, Rokusuke Tanaka, is to meet with the industry leaders Saturday in a new attempt to gain their assent. A decision is not expected until next week.

But the strong opposition to any cutbacks by industry leaders indicates that the ministry will have a hard time getting the auto makers to go along. After the results of yesterday's meeting were circulated, one industry official said that the ministry "will have a hard time persuading us."

There was reason to believe, however, that the position adopted yesterday may not be the final one. "It could depend on the pressure Tanaka is able to bring," an industry official said.

It is unusual for the industry to disclose its fundamental position on such a key issue and a spokesman for Toyota Motor Sales, Inc., denied that any agreement had been reached. There was also speculation that the news accounts were inspired by the auto makers' wish to proclaim a tough public bargaining position on the eve of the crucial meetings with the minister.

The basic agreement, the sources said, was that the industry should promise to restrain its exports to the 1980 level of 1.82 million passenger cars. Legislation pending in the U.S. Congress would require a cutback to 1.6 million cars. It is reported, without confirmation, that the ministry will propose about 1.7 million exports.

Anything less than the 1980 level of exports to the United States would hurt the Japanese industry and its parts suppliers and probably provoke antitrust suits by its American dealers, the industry's leaders argued yesterday.

They agreed that any voluntary restraint should last no more than one year. One industry leader contended that holding exports to last year's level for one year would in effect amount to a voluntary reduction because if left uncontrolled they could expect to increase sales this year by between 100,000 and 200,000 cars.

It also was argued that any volumtary cutback in U.S. sales would provoke an angry reaction in Europe, where several countries might demand a similar reduction of sales in their markets.

It is not yet clear how the ministry could force the auto makers to cut exports. Officials have at times talked of invoking an export control law, a drastic measure for a country that tries to make major decisions through industry-government consensus.

But the industry may need such a law for its own protection since a voluntary restrain could make it vulnerable to U.S. antitrust suits.

The Japanese industry has been critical of the ministry, contending that it is knuckling under to American pressures for political reasons when economic considerations do not justify cutting exports.

The Reagan administration has not directly and publicly asked for an export cutback, but has warned that unless Japan acts voluntarily it will face congressional quotas that may be worse. But the administration also has made it clear that President Reagan would find it difficult to veto a quota bill, and the Japanese regard this as direct political pressure.

A resolution may come next week after high level meetings involving Prime Minister Zenko Suzuki. He meets Monday with the Japanese ambassador to Washington, Yoshio Okawara.

Meanwhile, the Japenese government said today it has asked William Brock, the U.S. chief trade representative, to come here for conference before the final decision is made. The U.S. Embassy said Brock "has no plans to visit Japan at this stage."

A decision soon is crucial for Suzuki, who is scheduled to meet with Reagan during a state visit to Washington in early May.