China has urged all parties in the Korean standoff to stay calm and "stop irritating each other", a day after North Korea said the United States was pushing the region to the brink of nuclear war.
US Secretary of State Rex Tillerson said yesterday that Washington was working on more sanctions against North Korea if Pyongyang takes steps that merit a new response.
He also warned other countries that their firms could face so-called secondary sanctions for doing illicit business with Pyongyang.
Tillerson said the Trump Administration had been "leaning hard into China ... to test their willingness to use their influence, their engagement with the regime".
Diplomats said this week that Washington was negotiating with China on a possible stronger UN Security Council response to North Korea's missile tests.
Chinese Foreign Ministry spokesman Geng Shuang said UN resolutions were clear that further measures would be taken in the event of more nuclear or missile tests.
Chinese Foreign Ministry spokesman Geng Shuang called the situation "highly complex" and sensitive.
"The urgent task is to lower temperatures and resume talks," he said.
"We again urge all relevant parties to remain calm and exercise restraint, stop irritating each other, work hard to create an atmosphere for contact and dialogue between all sides, and seek a return to the correct path of dialogue and negotiation as soon as possible."
Meanwhile, US officials have said the US military's Thaad anti-missile defence system has reached initial operational capacity in South Korea, although it would not be fully operational for some months.
China has repeatedly expressed its opposition to the system, whose powerful radar it says can reach inside Chinese territory, even as Trump has praised Chinese President Xi Jinping for his efforts to rein in North Korea.
Trump has urged other Asian countries to help pressure North Korea.