The idea was apparently to deliver some kind of slow-acting poison, possibly at a military parade, that would kill the North Korean leader over the course of six months to a year.
"We will ferret out the last one out of the fanatic terrorists of the USA imperialist Central Intelligence Agency (CIA) and the puppet National Intelligence Service (NIS) who targeted the dignity of the DPRK supreme leadership, and mercilessly destroy [them]".
While the CIA has a notorious history of attempting to execute assassinations of political leaders across the world, the intelligence agency was forced to stop such operations in the 1970s after a Senate inquiry concluded that the policy was counterproductive.
It said a terrorist group backed by the Central Intelligence Agency and South Korean spies had entered the country for the attempted assassination, vowing that an "anti-terrorist attack" would begin "from this moment".
The ministry threatened that a counter-attack would begin immediately.
"This bill gives the administration a powerful tool to cut off North Korea's funding by going after those who do business with the regime", Chairman Royce said.
But he also said this week he would be willing to meet Kim Jong-un, in the right circumstances.
China on Friday opposed unilateral sanctions on North Korea by Washington, a day after the US House of Representatives approved a law granting more power to the executive to take such a step.
The allegation comes at a time of heightened tensions between North Korea and the United States, as well as its allies.
Supporters said the legislation was meant to send a strong message to North Korea, amid worldwide concern over the escalation of its nuclear program.
US President Donald Trump has promised to "solve" North Korea and stop it developing nuclear weapons.
FILE - In this Saturday, April 15, 2017, file photo, North Korean leader Kim Jong Un waves during a military parade in Pyongyang, North Korea, to celebrate the 105th birth anniversary of Kim Il Sung, the country's late founder and grandfather of current ruler Kim Jong Un.
KCNA noted that Kim looked at South Korea's Yeonpyeong Island from an observation post on Jangjae and received a report about recent "enemy movements" there.
On Friday, a spokesman for North Korea's Foreign Ministry called Gardner's remarks a "provocation that can not be overlooked" and an affront to the dignity of the country's supreme leadership, from a man who was "tantamount to mentally deranged". Both nations have continued to lob threats of a pre-emptive strike should either get word that the other was planning any military action.