Washington had previously claimed that Russia approached cash-strapped North Korea to buy a cache of ammunition to strengthen its military. Moscow denied the allegations and called them "fake".
A top North Korean defence official on Thursday told the US to stop making “reckless remarks” and to “keep its mouth shut", according to state media KCNA.
"Recently, the US and other hostile forces talked about the 'violation of a resolution' of the UNSC [United Nations Security Council], spreading a 'rumour of arms dealings' between the DPRK [Democratic People's Republic of Korea] and Russia," KCNA quoted the country's vice director general of the National Defence Ministry’s general equipment bureau as saying, without naming the official.
The official added that Pyongyang has never recognised the “unlawful” UNSC sanctions that were “cooked up by the US and its vassal forces”.
The official stressed that the export and import of military equipment is a “lawful right peculiar to a sovereign state”.
“But we take this opportunity to make clear one thing. We have never exported weapons or ammunition to Russia before and we will not plan to export them,” said the official.
A US State Department spokesperson earlier in September said that Russia was in the process of "purchasing millions of rockets and artillery shells from North Korea for use in Ukraine".
However, White House national security spokesperson John Kirby later clarified that there were "no indications" that the "potential purchase" was "completed and certainly no indications that those weapons are being used inside of Ukraine".
The North has used the war in Ukraine to tighten its relation with Russia to place a unified front against Western powers. The hermit kingdom has blamed the US for the crisis and the West's “hegemonic policy” to justify Russia's military action.
The North Korean government has reportedly hinted at its interest in sending construction workers to help rebuild pro-Russia breakaway regions in the eastern part of Ukraine.
Mr Putin last month in a letter to the North's supreme leader Kim Jong-un said that the two nations with their defence systems based on Soviet roots will "expand the comprehensive and constructive bilateral relations with common efforts".
Mr Kim responded with a letter, saying that the “strategic and tactical cooperation, support and solidarity” between the two countries had reached a new level amid threats and provocations from “hostile military forces”.