SAN FRANCISCO, SEPT. 16 -- A top federal trade official today accused major U.S. banks of failing to meet the needs of American exporters attempting to sell their goods in foreign markets.

"We are finding some foreign banks of one country financing exports of the United States to a third country," said John A. Bohn Jr., chairman of the U.S. Export-Import Bank.

"They're essentially prepared to take the risk of those markets more than {is} the American side," Bohn told the President's Export Council, holding its semiannual meeting in San Francisco.

Bohn said that foreign banks have frequently shown more enthusiasm for U.S. government trading programs than have American banks.

"If it moves a U.S. export, so much the better," said Bohn, whose agency supports trade by offering export financing, guarantees, insurance and low-cost loans.

Bohn said deregulation, the erosion of the barrier between commercial and investment banking, and the Latin American debt crisis have "badly shaken" the U.S. banking system.

Bohn said major banks now face "intense pressure" to boost their equity capital instead of financing risky projects abroad.

"The trade business does not produce the quick-profit, high-glamor kind of stuff that Wall Street does," Bohn said, adding he believes there is a lack of talented bankers working in the area of international trade.

Bohn said regional banks, which increasingly "outperform" major money center banks, are mindful of the Federal Reserve Board's focus on capital adequacy and are thus reluctant to finance trade deals, except "for very important clients."

Bohn also said he expects the U.S. trade deficit, which rose to a slightly worse-than-expected $16.5 billion in July, to show some improvement in September or October. He predicted exports of transportation equipment, especially aircraft, communications equipment and perhaps agriculture will be up in the fall.

Others at the meeting of the council, a group of top-level industry executives that advises President Reagan on trade matters, voiced frustration over a variety of American exports from fish to high-tech electronics.

Trade officials from California and Alaska, whose economies are heavily dependent on exports, said state industries need more support from the federal government and from U.S. negotiators at an international round of trade talks taking place under the General Agreement on Tariffs and Trade in Geneva.

"California firms need to achieve real progress in the new round {of talks}," said Robert D. Kleist, president of the California Council for International Trade, citing barriers to exports of high-quality California farm crops.

Alaska's salmon industry needs research and development money to fend off competition from government-subsidized fish farmers in Norway, said John A. Smith, commissioner of the Alaska Department of Commerce and Economic Development.

Reports of unfair Japanese trading practices in the area of electronics got support from an unlikely source: Japanese-born Aki Sato, president of NASAM, the U.S. trading arm of Cleveland-based Banner Industries.

In a comment that elicited appreciative chuckles from a mostly American audience, Sato complained of "invisible politics, invisible practices" that have hampered his efforts to promote exports of U.S. high-technology and military equipment, such as aircraft, missiles and satellite parts.