Iran has been hit with several rounds of U.N. sanctions over its refusal to halt uranium enrichment. Tehran again rebuffed U.N.-drafted proposals at talks in Istanbul in January, generating speculation about more economic pressures.
But Russian Foreign Minister Sergey Lavrov said that "any new proposals ... would basically be aimed at suffocating the Iranian economy."
He said that "was not part of the agreement" when the U.N. Security Council's five permanent members and Germany started trying to allay doubts over Iran's nuclear intentions with a combination of incentives and pressure.
Lavrov argued that the Istanbul meeting was "not a total failure." And Deputy Prime Minister Sergei Ivanov also insisted that there is "very limited and fragile progress," while emphasizing that Russia was against a nuclear-armed Iran.
"There is no alternative to further talks," Ivanov said at a security conference in Munich. "We believe that neither stronger sanctions nor the threat of or, more than that, the use of force can be considered as an effective tool."
Ellen Tauscher, the U.S. undersecretary of state for arms control, said that "the door remains open to negotiations." But she added "the United States will not settle for empty diplomacy and talks meant to delay and avoid responsibilities."
Low-enriched uranium can be used to fuel a reactor to generate electricity, which Iran says is the intention of its program. But if uranium is further enriched to around 90 percent purity, it can be used to develop a nuclear warhead.