From the NYT:
Imposing tougher sanctions on Iran over its nuclear program is a poor idea while diplomatic negotiations remain possible, Zhang Yesui, the Chinese ambassador to the United Nations, said Tuesday…Efforts to reach an accord with Iran over its nuclear ambitions need “some more time and patience,” he said, noting that senior political officials from the five permanent members of the Security Council and Germany were expected to meet in the coming weeks to discuss the next steps.
Mr. Zhang said remarks by Iranian officials over the past few days indicated their interest in finding a diplomatic resolution. “This also represents that there is more to happen in the area of talks,” he said.
China has long opposed using the Security Council to impose sanctions, particularly economic sanctions in countries where it has strong business interests. The Chinese buy about 15 percent of their oil from Iran… China and Russia, which has also expressed reservations about new sanctions on Iran, supported three previous Security Council resolutions that authorized sanctions aimed at Iranian individuals and organizations involved in the nuclear effort. The sanctions were devised to prevent Iran from developing nuclear weapons, which the government denies seeking.
See also the Chinese mission’s biography of Zhang Yesui.