North Korea said it took the measure because the USA didn't respond to its demand to withdraw sanctions announced last Wednesday on Kim for alleged human-rights abuses.
The North's Foreign Ministry reacted angrily to the sanctions, blasting the blacklisting as an "open declaration of war" and threatening to cut off all diplomatic channels with the USA unless the designation is revoked immediately.
In addition to cutting off communication, North Korea said it would treat all Americans detained in the country under "wartime law", without elaborating on what that means for those it is now holding.
USA experts said the North's reaction is not surprising.
North Korea on Sunday made the statement in a message to the United States denouncing recent sanctions against Pyongyang, which "impaired the dignity of the supreme leadership" of the country, Xinhua news agency reported.
It follows rising tensions last week on the Korean peninsula, after the US and South Korea pledged to deploy an advanced anti-missile system to counter the threats from North Korea. "This decision is especially bad for the detained Americans as the negotiations for these cases often used the NY channel". The sanctions targeted a range of assets, including property under US jurisdiction.
It remains unclear how that might affect the cases of Kim Dong-chul, a Korean-born American who's serving a 10 year hard labor sentence after being convicted of spying in April, and Otto Warmbier, an American serving 15 years of hard labor for attempting to steal a banner from his hotel in the Korean capital. The other senior officials targeted were Choe Pu II, head of the Ministry of People's Security; Ri Song Choi, a counselor in the Ministry of People's Security; and Kang Song Nam, bureau director at the Ministry of State Security.
Relations between North Korea and the USA, like those between Pyongyang and Seoul, are at their lowest ebb in several years, as the allies and North Korea have hardened their positions toward each other. The US maintains 28,500 troops in South Korea, a legacy of the 1950-53 Korean war.
North Korea rejected the sanctions and called for them to be removed.
North Korea conducted its fourth nuclear test in January and launched a long-range rocket the following month, resulting in tough new United Nations sanctions.
Also, on Thursday night, the United States announced that it reached an agreement with South Korea to deploy a Terminal High-Altitude Area Defense (THAAD) battery to the peninsula in response to North Korea's growing nuclear and missile capabilities.
"Although the NY channel has not proven particularly useful for the most part, if the DPRK sees it as in its interest to communicate with the United States, I'm sure it will find a way to do so", he said.