State Department Spokeswoman Jennifer Psaki made the comments in response to reports that the DPRK threatened to attack South Korea "without any notice " in retaliation for anti-DPRK rallies in South Korea.
Making a threat will "undermine international efforts to ensure peace and stability in Northeast Asia," she said.
According to South Korean sources, the DPRK's National Defense Commission on Thursday warned of retaliation against South Korea "without any notice," accusing the latter of insulting its "highest dignity."
On Tuesday, some people in South Korea burned effigies of the DPRK leader in protest against the DPRK.
Chinese Foreign Ministry Spokeswoman Hua Chunying said Friday that China has noticed reports about the issue and opposes any activities that undermine peace and stability on the Korean Peninsula.
"We hope all relevant parties remain calm and refrain from taking any action or making any comment that may exacerbate tensions on the peninsula," Hua said.
"Maintaining peace and stability on the peninsula is in the interests of all parties and also constitutes their common responsibility."