The Reagan administration is firmly opposed to boosting resources for the International Monetary Fund at this time, a U.S. Treasury official said yesterday, taking direct issue with a suggestion by IMF's managing director, Michel Camdessus.

Camdessus implied in a speech Tuesday in Singapore that a proposed liberalized lending policy would require larger contributions from member countries such as the United States.

"The IMF's resources are currently ample," the Treasury official said. "We now have a proposal for a general capital increase for the World Bank before Congress that must take priority over any possible increase in fund quotas {deposits by members}."

Camdessus had outlined a plan to give middle-income countries an advance pledge of funds if they committed themselves to undertake difficult policy reforms. He suggested that if the IMF, as a consequence, lent additional money, it would need more resources.

The Treasury official said that while the United States does not take issue with the general thrust of Camdessus' new proposals -- and in fact believes they are based in large part on ideas that Treasury Secretary James A. Baker III put forward at the last IMF annual meeting -- they should not result in a massive increase in IMF lending.

He acknowledged that some nations will press for a boost in the fund's overall lending authority at the next annual meeting in September. "But since the U.S. has a veto on this issue, there won't be a quota increase unless the U.S. signs on board," he said.

On a related issue, the Reagan administration reiterated its opposition to Soviet participation in the IMF, the World Bank and the General Agreement on Tariffs and Trade (GATT). An annual report titled "National Security Strategy of the United States," sent to Congress yesterday, asserts that "the Soviet economic system remains at this point fundamentally incompatible with participation in (such) free-world institutions."

It added that recent Soviet policy statements on economic reform "must be translated into positive actions before such participations can be considered."

Soviet leaders from time to time have expressed an interest in joining these institutions. A direct overture for membership in the GATT, just prior to the beginning of the current round of negotiations in 1986, was rebuffed by the United States. Later, a suggestion by World Bank President Barber Conable Jr. that if the Soviets expressed interest in joining the bank, it would be studied, was knocked down by Baker.

In discussing Soviet changes under party chairman Mikhail Gorbachev, the report said proposed domestic reforms are "sometimes placing Western governments on the defensive. ... Whether recent changes constitute a real opportunity for more fundamental improvements in relations with the Soviet Union remains to be seen. We are open-minded on this score."