After a six-year freeze, Cabinet-level meetings between the United States and the Soviet Union on trade issues are likely to resume, a U.S. Commerce Department official said here today.

"It seems to me there is reason for optimism," said Undersecretary of Commerce Lionel H. Olmer at a press conference winding up 2 1/2 days of talks with Soviet trade officials.

Olmer, heading a delegation of 10 U.S. officials, said the main purpose of his visit was to determine if a meeting of the Joint U.S.-U.S.S.R. Commercial Commission would be worthwhile. The commission, chaired by U.S. Commerce Secretary Malcolm Baldrige and Soviet Foreign Trade Minister Nikolai Patolichev, has not met since December 1978.

A final decision has not yet been made, but Olmer said his meetings here with Patolichev and Vladimir Sushkov, deputy foreign trade minister and head of the Soviet delegation, indicated that a ministerial meeting was possible.

"It seemed there are a number of areas where we can talk usefully and productively about expanding nonstrategic trade," Olmer said.

Official U.S.-Soviet contacts on trade issues were broken off after the Soviet invasion of Afghanistan in December 1979. Since then, trade relations have been buffeted first by a U.S. embargo on grain sales and then, after martial law was declared in Poland in December 1981, by a U.S. effort to block the sale of equipment for a Siberian natural gas pipeline.

The 1980 grain embargo has since been lifted, replaced by a five-year grain agreement signed in 1983, and U.S. companies now can sell pipe-laying equipment to the Soviet Union, provided it is not considered "strategic," Olmer noted today.

But U.S.-Soviet trade is still below what it was in 1979. According to the Soviet news agency Tass, the United States has fallen from second to seventh place among the Soviet Union's capitalist trading partners.

While citing a potential for "significant expansion" in U.S.-Soviet trade, Olmer noted that even in 1979, U.S. manufacturing exports to the Soviet Union were $700 million, a fraction of U.S. world trade. "It's not great when measured against half a trillion dollars in exports and imports," Olmer said.

This week's talks focused on ways to improve the trading climate and to ease business contacts within the framework of existing restrictions, Olmer said.

He singled out agribusiness, petrochemicals and consumer products as fields where U.S. business groups felt American firms could meet Soviet needs. The Soviets, for their part, want to increase their exports to the United States, but were not explicit about the type of products, Olmer said. Conceding that the U.S. market for Soviet goods is "very small," Olmer said, "The problem of marketing Soviet goods is a Soviet problem."

Restrictions on the sale of "strategic" goods and technology, as well as longstanding preconditions on granting the Soviet Union most-favored-nation trading status, were not discussed this week, Olmer said.

"There is no intention, no sentiment, no interest in pursuing changes" in those areas, he said. The United States has tied most-favored-nation status to greater freedom for Soviet citizens to emigrate and has signed agreements with 14 nations limiting the transfer of technology to Warsaw Pact countries.

Olmer said the Soviets were not aware that the 15-nation committee that monitors sensitive exports to the Soviet Bloc had changed its rules recently to allow the sale of personal computers to countries in the bloc. Those changes were adopted along with tighter restrictions on the sale of more sophisticated computer technology.