The Reagan administration accused Soviet leader Mikhail Gorbachev yesterday of making a "distorted characterization" of the Geneva arms control talks and a "thinly veiled threat" to suspend the negotiations on reducing nuclear weapons.

State Department spokesman Edward Djerejian, rejecting criticisms Gorbachev made Wednesday of the U.S. position in Geneva, denied the Soviet leader's charge that the American delegation is "marking time" and delaying progress. Djerejian defended the U.S. position in the talks as "constructive" and "flexible."

"It is the Soviet Union and not the United States that is marking time in the negotiations," Djerejian said. "After almost two full rounds of talks, we have yet to see any concrete new proposals for the reduction of offensive nuclear arms, or to engage in a serious discussion of the constructive and flexible positions put forward by the United States."

Gorbachev hardened ongoing Soviet criticism of the U.S. role in Geneva in a speech delivered Wednesday in the Ukrainian city of Dnepropetrovsk and televised in the Soviet Union. Speaking to metalworkers, Gorbachev said the Soviets would have to "reassess the entire situation" if U.S. negotiators continue to "carry on their line, marking time."

The latest cross-fire between Moscow and Washington has appeared to tighten the deadlock gripping the talks since their opening in March. Reacting to the specter raised by the possibility of a Soviet reassessment of its role in the talks, the State Department spokesman said at a briefing that the Soviet Union set back negotiations by more than a year when it walked out of the talks at the end of 1983.

Djerejian, reading from a two-page response, said the United States is "astonished" by Gorbachev's "distorted characterization of the Geneva negotiations . . . and by his thinly veiled threat to suspend the talks."

Djerejian also said that the Soviet negotiators have "refused to engage in a constructive discussion of the potential that defensive technologies could make," an apparent reference to the Reagan administration's plans for research in the Strategic Defense Initiative (SDI), commonly known as "Star Wars."

Moscow has mounted a persistent campaign against the SDI, arguing that it would violate the 1972 Antiballistic Missile (ABM) treaty and that the U.S. refusal to abandon the concept has hampered progress at the Geneva arms talks.

Accusing the Soviet Union of "hypocrisy," Djerejian said it has "been engaged for many years and at a higher level of effort in the sort of research on strategic defense now being undertaken by SDI," and that the Soviet Union is undermining the ABM treaty by constructing a radar at Krasnoyarsk, in central Siberia.

Djerejian denied Gorbachev's charge that the United States is using the Geneva talks as a cover for military programs.

Despite the sharp language of the U.S. statement, Djerejian said both sides want a meeting between President Reagan and Gorbachev. "A time and a place for such a meeting" has yet to be decided, he said.