The White House scene described by Masayoshi Ito sounded like two politicians getting together to lay out their problems to each other. But in many ways the Japanese foreign minister's discussion with Ronald Reagan this week about Japanese automobile sales in the United States represented a serious growing clash between two very different cultures and economics.

In a low-key but clear warning, Reagan told Ito that it would be very difficult for an American president to veto a bill with protectionist features in the present climate of concern about automobile imports. In equally polite but transparent terms, the Japanese official told the American president that no Japanese government could ask its industry to make sacrifices when deep and apparent divisions on this question existed in Reagan's own Cabinet and in American public opinion.

Ito's description of the Tuesday meeting made it clear that he had not come to haggle over 100,000 cars more or less but rather to tell Reagan that the solution to the massive problems of the American automobile industry lies in Detroit rather than in Tokyo.

A newly assertive Japanese government was suggesting that it could do nothing until the U.S. automobile industry adopted an ambitious and comprehensive revitalization program that would probably benefit from following Japan's own experience in productivity increases and wage and price discipline.

Behind this assertiveness is the economic weight of the fact that Japan last year surpassed the United States as the world's largest automobile manufacturer. Japanese officials and industrialists are convinced that their society's attitude toward work, wages and productivity enabled Japan to achieve this, and increasingly they suggest to their American counterparts that only a complete transformation of American work habits and production systems will restore the United States to a position of global economic leadership.

Ito's visit seemed to some of the reporters he met with over lunch after seeing Reagan to reflect an important moment of transition for Japan, which is slowly but perceptibly moving away from the junior partner role in which it has been cast, and which it has felt comfortable playing, in the years since World War II.

With elaborate precautions, the Japanese are minimizing the frictions that such a movement inevitably brings, but they are also being insistent on some points on which previous Japanese governments would have yielded far more readily.

Ito seemed somewhat bemused by the high level of anxiety and amount of detail thrown at him by American officials, particularly by Secretary of State Alexander M. Haig Jr.

Haig's late and characteristically high-volume entry into the auto talks appears to have contributed to the Japanese government's decision not to discuss substance with Washington until the Reagan administration demonstrates that it has a clear and agreed-upon course of action on the U.S. automobile industry.Then, Japan will be ready to be consulted on how its actions can complement that policy.

The Japanese minister repeatedly asked, by his account, for details on what the president's Cabinet-level task force on the U.S. automobile industry was going to recommend. He repeatedly got vague answers, again by Ito's account, and he and the president turned the conversation into a discussion of the virtues of the free trade system.

The task force has been badly split over the question of imposing quotas on automobile imports if Japan does not adopt voluntary restraints that will reduce the total from last year's 1.9 million, a figure that means that one out of every five cars sold in the United States last year was made in Japan. Its discussions have become stuck on the question of imports and not moved into the kind of comprehensive reforms that Ito suggested were necessary.

Pressed to enumerate the changes that the task force could recommend that would give Japan's government ammunition for the battle it would have to fight at home over export restrictions, Ito said he did not know enough about the U.S. auto industry to be specific.

Ito then went on to say, however, that he had talked to Reagan about the fact that the workers in Japan's auto industries and their unions had kept wage increases in the same range as annual productivity increases. He noted that last year the auto workers settled for a 6.8 percent increase in wages. He also repeated the widely held view that Japanese workers see their future employment tied very closely to the success of the company they work for and are prepared to make sacrifices to ensure the company's health in return for guaranteed lifetime employment.

This appeared to be as close as Ito came to discussing specifics in Washington. He said that at a meeting in Tokyo with Prime Minister Zenko Suzuki and other officials last week, it had been agreed that he would listen to American ideas but not respond with any Japanese proposals for voluntary restrictions. He was apparently taken aback by Haig's forceful presentation.

Ito recounted that he had told Haig that he was aware that the secretary had been a general and knew about military matters, that he was secretary of state and knew about diplomacy, and that Haig had been a football player and knew about sports. Ito was surprised, however, to discover that the secretary of state knew so much about automobiles as well.