The State Department said Wednesday that the United States would be open to talking to North Korea "when the time is right" but that it could not happen now because Pyongyang has shown no sign of a willingness to halt its missile and nuclear testing, Reuters reported.
State Department spokeswoman Heather Nauert said there would first have to be a "period of calm" in which Pyongyang suspends testing before any negotiations could begin.
Her comments follow U.S. Secretary of State Rex Tillerson's offer on Tuesday to start talks with North Korea without preconditions.
Tillerson, in a speech to a Washington think tank, did not explicitly establish such a freeze as a requirement that North Korea must meet ahead of talks.
Nauert, who spoke at the State Department's daily briefing, insisted that Tillerson was not establishing new policy in his speech, even though he appeared to back away from a key U.S. demand that Pyongyang must first accept that any negotiations would have to be about giving up its nuclear arsenal.
Meanwhile, a White House official told Reuters there can be no negotiations with North Korea until it "fundamentally improves its behavior.”
"Given North Korea's most recent missile test, clearly right now is not the time (for negotiations)," the White House National Security Council spokesman told the news agency.
Tensions on the Korean peninsula have risen markedly in recent months after North Korea’s latest missile and nuclear tests, conducted in defiance of international pressure and United Nations resolutions.
Most recently, North Korea launched a Hwasong-15 missile, a new type of intercontinental ballistic missile (ICBM) which officials said can fly over 13,000 km (8,080 miles).
Pyongyang said following the launch that it had test-fired its most advanced missile, putting the U.S. mainland within range.
The isolated country also declared itself to be "a responsible nuclear power" and said its nuclear weapons were developed in order to provide protection from "the U.S. imperialists’ nuclear blackmail policy and nuclear threat."