Sen. Henry M. Jackson (D-Wash.) said yesterday that the United States and other Western countries should continue using economic pressure to persuade the Soviet Union to loosen its emigration restrictions against its Jewish citizens.

Jackson, in an address to the leadership meeting of the National Conference on Soviet Jewry, said the Russians are vulnerable to such pressure.

"I am convinced that as the Soviets face mounting economic problems in their foreign borrowings, they will eventually decide that it is better to loosen their emigration policies than to continue the statement on trade and credits," he said.

Jackson said the Soviet Union together with the Eastern bloc nations "has incurred a debt of over $44 billion to the West."

He said he does not think it unreasonable to link international trade agreements to freer emigration from the Soviet Union and Eastern Europe, as he did in an amendment to the Trade Act of 1974.

"That amendment was just a bit of hard bargaining. It just says that if you give something, you ought to get soemthing in return," he said.

The amendment was criticized by many American business interests as being harmful to the development of lucrative U.S.-Soviet trade relations. The Russians rejected the terms it imposed for trade and also decided to void a 1972 trade agreement with the United States that had helped to open up dicussions on detente.

However, Jackson and Sen. Jacob R. Javits (R.N.Y.), who also addressed the conference yesterday at the International Inn, denied allegations that the amendment undermined U.S. Soviet trade.

Jackson warned that "business groups who seek to profit from [U.S.] government-subsidized sales to the Soviet" are still working for the repeal of the amendment. "But we have international law on our side," he said, referring to the 1975 Helsinki accords in which the United States, Canada, the Soviet Union and 32 European countries agreed to respect human rights.

Javits, taking note of the Soviets criticism of the Jackson amendment, said the Russians used the measure "as a convenient handle to back out "of" earlier trade pacts paving the way to detente. He urged Americans, in general, and the American Jewish community, in particular, to support Jackson's position.