Japanese Foreign Minister Yoshio Sakurauchi said today that Japan is set to enforce more sweeping steps to open its markets to foreign products before the June economic summit in Paris and will support new Reagan administration initiatives toward Central America and the Caribbean by boosting its economic aid to the region.

In a 70-minute interview shortly before his departure for talks in Washington, the senior diplomat appeared to set the stage for attempts to reaffirm the mostly friendly ties with Japan's key Pacific ally that have been badly strained by the country's booming surpluses on trade with the United States.

Sakurauchi noted that Japan and the United States now account for 35 percent of the world's total gross national product and said the two countries "have great contributions to make to the world economy." He said the huge trade gap between them "is something that must be resolved" and cited the need to further open the Japanese market as a "major problem for which we have the responsibility."

In the background is the record $18 billion U.S. deficit in trade with Japan in 1981 that has brought dire warnings from American trade officials that the Japanese should move quickly to open their markets to more foreign goods or face the enactment of protectionist legislation.

In a bid to avert a showdown on trade, Prime Minister Zenko Suzuki's Cabinet has moved to slash tariffs on 1,650 items in advance of an agreed schedule. It has also made efforts to dismantle a number of so-called "non-tariff barriers" to trade and to streamline customs and product standards and testing procedures that foreign businessmen frequently claim bar them from successfully competing in the Japanese market.

These measures have so far failed to impress U.S. trade officials who, earlier this week, renewed demands that Japan take more "dramatic" steps before the Paris economic summit.

Reflecting an apparent 11th-hour decision by Japanese leaders on the eve of his talks with U.S. officials, Sakurauchi said today, "we will make all necessary efforts" toward developing a new package of trade measures.

Sakurauchi gave no specifics. He pointed out that as a result of trade talks here this month, Japan has agreed to begin deliberations with American officials next month on most of the 27 remaining quota restrictions on imported goods and to start negotiations on beef and citrus-fruit imports in October, six months ahead of schedule.

Sakurauchi said the movement toward resolving outstanding trade problems is "now on track" in Japan, but expressed concern about whether the Reagan administration would regard Japan's cumulative efforts on trade before the Paris summit as "dramatic" enough.

Yet Sakurauchi also called on the United States to exercise stronger leadership among the industrialized nations.

"We are often told by the American side," he said, "that the Japanese government should make efforts to reduce the trade imbalance, but the United States should also put emphasis on the issues of the world economy and have a policy for dealing with its revitalization."

Sakurauchi did not elaborate, but the consensus here is that continuing high interest rates in the United States have helped aggravate Japan's trade surpluses by driving down the value of the yen and adding to the attractiveness of Japanese exports by reducing their costs abroad.

Saburo Okita, a former foreign minister and an economist, said this week that "high interest rates in the U.S. are the cause of the worldwide recession and also the trade imbalance." While Japan is being blamed for rising joblessness in the United States and Western Europe, he asserted, "the major reason . . . is the zero growth" of the American and European economies. He said Japan's role in creating global economic ills was "only marginal."

In light of President Reagan's plans to boost economic aid to the Caribbean basin, Sakurauchi said, "We wish to expedite our economic cooperation with these countries in order to improve the welfare of the people and the economic situation."