Japanese Prime Minister Masayoshi Ohira arrived in Washington yesterday for a two-day state visit that begins officially Wednesday with talks with President Carter.

It will be the first meeting between the two men in their capacities as leaders of their countries.

American officials went out of their way yesterday to soften the tensions that have arisen between the two countries over Japan's large trade surplus and more specifically, a limit Japan is placingon competitive bidding in government procurement of telecommunication equipment.

Special Trade Representative Robert Strauss stressed in a telephone interview that "we have not broken off discussions on this issue. We're acting in good faith and somewhere along the line we'll reach agreement."

Japan had offered to open up $7.5 billion worth of orders placed by Nippon Telephone and Telegraph Co. to competitive bidding. After Strauss rejected the offer as inadequate because it did not include about $800 million in sophisticated computers and other equipment, Ohira said Japan had made its best offer and nothing else would be forthcoming.

Strauss then told the House Ways and Means Committee that if Japan did not enlarge its offer, some $12.5 billion in U.S. procurement that otherwise would have been open to Japanese bidders under the proposed multilateral trade treaty would be withheld.

There is no plan for this issue to be raised during the Carter-Ohira talks, and informed sources said further negotiations would be postponed until after this week. But it is hoped that it will be resolved before the heads-of-state summit in Tokyo late in June.

Nevertheless, Japanese sources indicated Ohira will review the record of what the Japanese government believes have been substantial concessions to American pressures the past two years.

Advance material put out by the Japanese embassy, for example, notes that despite the perception that Japan is maintaining large trade and current account (which includes services as well as merchandise) surpluses, corrective measures have been bringing both down.

The global current account surplus in the first quarter of 1979, for example, was down to $300 million, a sharp drop from $5.1 billion in the first quarter of 1978. Their export volume, the Japanese say, was 11.2 percent lower than in the first quarter of 1978, while the import volume was up 15.1 percent.

American officials, on the other hand, maintain that these improvements-which they acknowledge-are not likely to be permanent unless Japan makes further efforts to open markets to imports of manufactured goods.

Ohira has a day of rest and private meetings scheduled today. The White House meeting Wednesday is expected to be followed by briefings by both Carter and Ohira. Secretary of State Cyrus R. Vance will host a Wednesday lunch at the State Department and there will be a formal White House dinner Wednesday night.

On Thursday, Ohira will host a breadkfast for top economic officials at Blair House, address a National Press Club lunch and visit members of Congress, many of whom have warned that openly protectionist measures against Japanese goods need to be considered. CAPTION: Picture, Prime Minister Masayoshi Ohira and wife Shigeko depart Tokyo. Foreign Minister Sunao Sonoda is behind Ohira. UPI