SEOUL, South Korea — North Korea said on Thursday that the United States had proposed resuming talks on denuclearization in December, but warned that Pyongyang was not interested unless Washington was ready to meet its terms. And a top envoy said he believed the proposal was merely “a trick to earn time .”

The North Korean envoy to the talks, Kim Myong-gil, said on Thursday that his counterpart in Washington, Stephen E. Biegun, had sent a proposal to the North through a third party. Mr. Biegun and Mr. Kim led their countries’ delegations to working-level talks in Sweden last month, which ended without an agreement.

In a statement that was carried by the North’s official Korean Central News Agency, Mr. Kim expressed strong doubt about Mr. Biegun’s sincerity, asking why the American envoy had sent his proposal through an intermediary rather than contacting him directly.

“If the negotiated solution of issues is possible, we are ready to meet with the U.S. at any place and any time​,” Mr. Kim said. But he added that North Korea had “no willingness to have such negotiations” if the United States merely planned to stall, as ​he said Mr. Biegun’s team had done in Stockholm​.