In response to such remarks, South Korea's presidential office expressed regret, and warned that this would only isolate the regime from the international community.
Seoul's Unification ministry said, though, that it will continue efforts to bring the North back to dialogue.
Min Suk-hyen reports.
South Korea has expressed deep regret over the latest remarks made by Kim Yo-jong, the sister of North Korean leader Kim Jong-un.
The presidential office released a statement just hours after Kim Yo-jong mocked President Yoon and called his economic aid plan for denuclearization "absurd."
The top office said it was very regrettable that North Korea continues to use such disrespectful language and continues to express its intent to develop nuclear weapons.
It warned that such an attitude would only isolate the regime from the international community and would not help achieve peace and prosperity on the Korean Peninsula.
The presidential office stressed that it remains firm in its pursuit of the North's denuclearization and the development of inter-Korean ties through the President's "audacious plan."
Seoul's Unification Ministry also expressed "strong regret" over Kim's statement, saying it distorted the purpose of President Yoon's "audacious" initiative.
"It is very regrettable. They criticized our president in a very rude and disrespectful way. Also, it's very regrettable that it distorted the audacious plan."
Unification Minister Kwon Young-se also stressed that this was neither beneficial for North Korea nor good for achieving peace on the Korean Peninsula.
Instead, Kwon urged the regime to return to dialogue, adding that he will continue to work towards that end.
On the same day, South Korea's Foreign Ministry also voiced concern over North Korea's refusal to take steps toward denuclearization.
During a phone call with U.S. Secretary of State Antony Blinken, Seoul's Foreign Minister Park Jin shared his concerns, and the two top diplomats agreed to closely work together to deter North Korea's provocations, while pushing for Pyeonyang's return to dialogue.
Min Suk-hyen, Arirang News.