Jiang Yu, a Chinese foreign ministry spokesman, said on Tuesday that a draft UN security resolution represented an overreaction and, if adopted, would exacerbate the problem.
"It will hurt efforts to resume six-party talks as well as lead to the UN Security Council splitting," he said.
The statement was issued amid a new round of diplomacy that also involved North and South Korea and the US.
Meanwhile, the Chinese president, Hu Jintao, said Beijing was "seriously concerned" about the issue of North Korea's missile tests.
"We are against any actions that will aggravate the situation. We hope that relevant parties will do more things conducive to the peace and stability of the peninsula," Hu said.
Backers of the Japan-sponsored draft UN resolution put off the vote for another day on Tuesday while Chinese officials visit Pyongyang.
The most senior US nuclear envoy to the six-party talks on North Korea's weapons programme made an unscheduled visit to China on Tuesday, saying that negotiations had reached a crucial point.
Christopher Hill said Washington was counting on Beijing to take the lead in lobbying North Korea to end its missile tests and return to nuclear talks.
"We have the DPRK [North Korea] which, instead of coming to the six-party process, is firing off missiles of all shapes and sizes, missiles that are aimed at not just us but countries in the region," Hill said.
North Korea said again on Tuesday that it will return to the six-party talks only if the US drops financial sanctions against it.
"As soon as the United States lifts financial sanctions, we will readily participate in the next round of the six-party talks," said the North Korean deputy foreign minister, Kim Hyong Jun.