"We will have dialogue if the U.S. seeks dialogue. If it seeks isolation, we will stand against it," nuclear negotiator Ri Gun told reporters after meeting with chief U.S. nuclear envoy Christopher Hill in New York on Thursday.
Seoul's Yonhap agency said the official's comments followed reports that President-elect Obama could send a special envoy to Pyongyang, to boost progress at the six-nation talks on the communist state's nuclear disarmament.
Ri, who heads the U.S. affairs bureau at North Korea's Foreign Ministry, met with Sung Kim, the U.S. special envoy to the six-party talks, and later with Christopher Hill.
"We've handled many U.S. administrations, some seeking dialogue with us and others trying to isolate and oppress us," Ri said after his meeting with Kim.
When asked to comment on reports that North Korean leader Kim Jong-il has suffered a stroke and is in a critical condition, the official angrily dismissed them as "utter nonsense."
Sung Kim said his meeting with Ri had focused on measures to verify North Korea's nuclear activities, and the provision of fuel aid to the North as part of a six-party deal, under which Pyongyang has agreed to dismantle its plutonium-producing Yongbyon reactor.
Hill said the sides had agreed to hold a new round of six-party talks as soon as possible.
Barack Obama, who will become U.S. president in January, is widely expected to seek more direct negotiations with North Korea.
In a September 2008 presidential debate, he said the Bush administration's lack of diplomatic engagement with the North had driven the country to build up its nuclear capacity.
The last Democrat in the White House, Bill Clinton, had expressed a willingness to visit North Korea, but the plans never materialized. His successor George W. Bush labeled North Korea an "Axis of Evil" state in 2002, and refused direct negotiations. Four years later, the North carried out its first nuclear bomb test.