North Korean Foreign Minister Ri Yong Ho said US President Donald Trump's threat to destroy Pyongyang sounded like "a dog barking".
"If he was thinking he could scare us with the sound of a dog barking, that's really a dog dream," Ri, who is here for the UN General Assembly, told the media on Wednesday night.
In Korean, a dog dream is one that is absurd and makes little sense.
Though Trump's speeches typically employ colourful rhetoric, threatening another country with destruction was unprecedented for a US President and took diplomats aback, CNN reported.
"The US has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea," Trump said in the Tuesday speech.
"North Korea's reckless pursuit of nuclear weapons and ballistic missiles threatens the entire world with unthinkable loss of human life... No nation on Earth has an interest in seeing this band of criminals arm itself with a nuclear weapon and missiles."
When asked about Trump's new nickname for Kim Jong-un as the "rocket man", Ri said of the US President: "I feel sorry for his aides."
North Korean diplomats were not present during Trump's speech, reports CNN.
Trump is scheduled to meet with Japanese Prime Minister Shinzo Abe and South Korean President Moon Jae-in Thursday.
The three leaders are expected to discuss North Korea.