North Korea on Monday rejected the new South Korean president’s proposal for talks, saying that his policy toward the North was no different ​than that of his ousted predecessor, under ​whom relations had plunged to the lowest point in years.

Since taking office on June 4, President Lee Jae Myung of South Korea has repeatedly ​said that he wanted to ease tensions on the divided Korean Peninsula by improving ties that deteriorated under his conservative predecessor, Yoon Suk Yeol.

As gestures of good will, Mr. Lee ​banned anti-North Korean activists from sending leaflets into the North by balloon. He also stopped the loudspeaker propaganda broadcasts along the border that had long angered Pyongyang.​ Earlier this month, South Korea even switched off shortwave radio broadcasts that had carried similar propaganda for over a half century.

But such efforts by Mr. Lee were “not the work worthy of appreciation,” said Kim Yo-jong, who speaks for her brother​, Kim Jong-un, ​the top leader of North Korea, in a statement carried in North Korean state media on Monday.