State Councilor Yang Jiechi made the remarks at the opening of a second day of meetings between Chinese officials and special envoy Lee Hae-chan, a former South Korean prime minister.
The agreement came after North Korea conducted its latest ballistic missile test Sunday, claiming the US was within its sights and it had the capability to fire a large nuclear warhead.
The weekend launch was the first since a new liberal president took office in South Korea.
"Whenever something odd happens, it is the stereotype way of the United States and the hostile forces" to kick off a "noisy anti-DPRK campaign" deliberately linking the country to it, said Kim In Ryong, deputy ambassador to the United Nations.
Protesters were rallying against Park's ties to a corruption scandal, and not against her responses to North Korea provocations or her commitment to the alliance with the United States.
Meanwhile, Kim rejected "ridiculous" allegations the WannaCry cyberattack that affected hundreds of thousands of computers around the world originated from North Korea.
"The new administration has the willingness to solve the North Korean nuclear issue based on a solid security and the [South Korea-U.S.] alliance", Hong told McMaster.More news: Macron as French President: Lesser of Two Evils
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Tuesday's agreement came as President Moon Jae-in's security advisers met with visiting representatives from the U.S. National Security Council ahead of a planned summit with U.S. President Donald Trump next month.
"Combining nuclear warheads with ballistic technology in the hands of a volatile leader like Kim Jong Un is a recipe for a disaster", Harris said.
He added, "We are well aware how much effort President Trump has put into leading China" to more actively rein in North Korea, emphasizing the importance of the South Korea-U.S. alliance in that process.
Friday's news conference came after a string of provocations by the North - seven test launches of ballistic missiles this year alone - generally followed by condemnation from the worldwide community.
Communications were severed a year ago, Lee said, in the wake of new sanctions following a fifth nuclear test and Pyongyang's decision to shut down a joint industrial zone operated inside the North.
Speaking to reporters ahead of the Security Council meeting, Nikki Haley, Washington's envoy to the United Nations, said that the USA would only talk to North Korea once it halted its nuclear programme.