In a speech at the Supreme People's Assembly, Kim said he still has fond memories of US President Donald Trump, KCNA also reported. The two leaders met three times during Trump's first presidency.
"If the United States drops the absurd obsession with denuclearising us and accepts reality, and wants genuine peaceful coexistence, there is no reason for us not to sit down with the United States," Kim was quoted as saying.
It was a matter of survival for North Korea to build nuclear weapons to safeguard its security in the face of grave threats from the United States and South Korea, Kim said.
He said he rejected recent overtures from Washington and Seoul for dialogue as insincere because their fundamental intent to weaken the North and destroy his regime remains unchanged.
He said a proposal by the South on ending the North's nuclear programs in phases was proof of that.
"The world already knows full well what the United States does after it makes a country give up its nuclear weapons and disarms," Kim said. "We will never give up our nuclear weapons.
"There will never be, and will never ever be for eternity, any negotiations with enemies of exchanging some things out of some obsession with lifting sanctions."
Sanctions have been "a learning experience" and made his country stronger and more resilient, Kim said.
North Korea has been under a series of UN Security Council resolutions imposing economic sanctions and arms embargoes that have squeezed funding for military development but it has continued to make advances in building nuclear weapons and powerful ballistic missiles.
South Korean President Lee Jae Myung told Reuters those sanctions have ultimately failed to deter the North, which is adding massive nuclear weapons numbering 15 to 20 to its arsenal every year.
"The reality is that the previous approach of sanctions and pressure has not solved the problem; it has worsened it," Lee said.
Lee has made peace overtures since taking office in June, saying dialogue with Pyongyang was necessary, and has proposed steps to build confidence and eventually end the North's nuclear program.
He said there are formidable obstacles to reopening dialogue with the North but he still believed the phased approach on dismantling Pyongyang's nuclear program was the realistic option.
It was necessary to create the right conditions to bring the North back to the table and Trump has a key role to play in those efforts, Lee said.
