Kim Yo Jong, who is a senior North Korean ruling party official and is believed to speak for the country's leader, said Lee's pledge of commitment to South Korea-US security alliance shows he is no different from his hostile predecessor.
"If South Korea expects to reverse all the consequences of (its actions) with a few sentimental words, there could be no greater miscalculation than that," Kim said in comments carried by official KCNA news agency.
Lee, who took office on June 4 after winning a snap election called after the removal of hardline conservative Yoon Suk Yeol over a failed attempt at martial law, has vowed to improve ties with Pyongyang that had reached the worst level in years.
In one measure aimed at easing tensions, Lee suspended loudspeaker broadcasts blasting anti-North propaganda across the border and banned the flying of leaflets by activists that had angered Pyongyang.
Kim, the North Korean official, said those moves are merely a reversal of ill-intentioned activities by South Korea that should never have been initiated in the first place.
"In other words, it's not even something worth our assessment," she said.
"We again make clear the official position that whatever policy is established in Seoul or proposal is made, we are not interested, and we will not be sitting down with South Korea and there is nothing to discuss."
