"We have nothing more to lose", Kim Yong Chol, a senior official in the Central Committee and chairman of the Korea Asia-Pacific Peace Committee, said in a statement published by the Korean Central News Agency.
He said that North Korea would not reconsider any of its plans in light of discouragement from the United States and warned that any US action on the Korean Peninsula would not go unanswered.
The most recent rift between Washington and Pyongyang follows the latter's successful test at the Sohae Satellite Launching Ground on Saturday, as well as two missile launches on 28 November.
On Sunday, Trump tweeted that Kim was "too smart and has far too much to lose ... if he acts in a hostile way". He further warned that the North Korean leader "does not want to void his special relationship with the President of the United States".
In 2018, relations between North Korea and the United States appeared to show signs of improvement as Kim Jong-un held direct talks with the presidents of South Korea and the United States. However, the negotiation process came to a standstill this year due to a lack of specific denuclearization measures and resumed missile tests.