In an apparent attempt to defuse the latest conflict over trade relations, Premier Masayoshi Ohira said today he expects to confer with President Carter in Washington this spring.

Ohira coupled his announcement with a strong defense of steps Japan has already taken to reduce its trade surplus, a message he is likely to repeat in detail when he meets Carter.

No date for the summit meeting has been set, but sources indicated that the most probable time is the first week of May.

It would amount to a climax of Japan's current campaign to persuade the United States that it has acted decisively to reduce its trade surplus and head off what Japanese leaders fear is a flood of protectionist legislation in Congress this spring.

Four high-level Japanese economic officials already have visited Washington this year to explain Japan's case in what is the most forceful effort so far to meet American criticism. Foreign Minister Sunao Sonoda is expected to visit Washington soon.

Ohir's trip is also designed to get some domestic political mileage. The premier has been criticized since taking office last December for failing to act decisively in the trade conflict. The controversy stems from Japan's of nearly $12 billion last year, far above previous Japanese predictions.

The press has accused him of bungling by announcing almost as soon as he took office that Japan was abandoning the long-publicized goal of reaching a 7 percent economic growth rate in the current fiscal year. He has since explained that he was merely recognizing realities of economic life by lowering that target to 6.3 percent.

The trip to Washington will amount to a kind of pre-summit for the two leaders. Carter is expected to meet in Tokyo with Ohira sometime in June, probably just before the economic summit meeting of Western industrial nations.

Ohira said at a luncheon with foreign correspondents today that the two countries should communicate to prevent economic problems from developing into political problems.

He said it is natural for trade problems to develop from time to time because of their differing economic structures and cultural patterns but they can be solved if approached with "calmness and steadiness."

The Japanese have been reacting to American criticism with more force-fulness and fewer apologies this time, insisting they already have taken many decisive steps to reduce the trade surplus in coming months.

A number of statistical indicators point now to a gradual lessening of the surplus but Japan fears that Congress may set out on a protectionist path before the trend has become decisive.