North Korean leader Kim Jong-un set a yearend deadline for denuclearization talks with the United States and White House National Security Adviser Robert O'Brien said at the time the United States had opened channels of communication, Reuters reported.
O'Brien said then he hoped Kim would follow through on denuclearization commitments he made at summits with US President Donald Trump.
US disarmament ambassador, Robert Wood, voiced concern at Pyongyang's latest remarks and said Washington hoped the North would return to the negotiating table.
Ju Yong Chol, a counselor at North Korea's mission to the UN in Geneva, said that over the past two years, his country had halted nuclear tests and test-firing of intercontinental ballistic missiles, "in order to build confidence with the United States".
However, the US had responded by conducting dozens of joint military exercises with South Korea on the divided peninsula and by imposing sanctions, he said.
"As it became clear now that the US remains unchanged in its ambition to block the development of the DPRK and stifle its political system, we found no reason to be unilaterally bound any longer by the commitment that the other party fails to honor," Ju told the UN-backed Conference on Disarmament.
Speaking as the envoy from the Democratic People's Republic of Korea (DPRK), North Korea's official name, Ju accused the United States of applying "the most brutal and inhuman sanctions".
"If the US persists in such hostile policy toward the DPRK, there will never be the denuclearization of the Korean Peninsula," he said.
"If the United States tries to enforce unilateral demands and persists in imposing sanctions, North Korea may be compelled to seek a new path."
North Korea warned in December that it may take an unspecified "new path" if the United States failed to meet its expectations with a new approach to negotiations.
Pyongyang has rejected unilateral disarmament and given no indication that it is willing to go beyond statements of broad support for the concept of universal denuclearization.
"The US behavior also threw a wet blanket over our efforts for global disarmament and non-proliferation of nuclear weapons," Ju said.
North Korea has said in previous, failed talks that it could consider giving up its arsenal if the United States provided security guarantees by removing its troops from South Korea and withdrew its so-called nuclear umbrella of deterrence from South Korea and Japan.