China and the United States agreed that stronger sanctions were needed against North Korea after Pyongyang's nuclear and missile tests in the past two months.
The move comes as the UN Security Council was expected to tighten sanctions against the country "in the coming days," according to a senior council diplomat speaking Wednesday.
The resolution was dependent on negotiations between the US and China, he said, speaking anonymously.
Later Wednesday, National Security Advisor Susan Rice met with Chinese Foreign Minister Wang Yi and agreed on the importance of "a UN Security Council Resolution that goes beyond previous resolutions," in response to the "provocations," the US National Security Council said.
China is the only significant international ally of the isolated, communist regime in North Korea, but relations have cooled in recent years amid increasing belligerence from Pyongyang.
North Korea tested a nuclear bomb in early January and launched a missile into space a month later, prompting Western countries to condemn both as a breach of restrictions on its nuclear weapons development programme.
The US has tightened its own measures implementing sanctions against those associated or trading with Pyongyang.
US President Barack Obama joined the meeting between Rice and Wang, held during Wang's visit to Washington, and said he looked forward to meeting Chinese President Xi Jinping at a nuclear security conference in the US in late March.