The diplomat, who spoke on condition of anonymity, said China, who for weeks stalled on holding such discussions, took part in the call with senior foreign ministry officials of Britain, France, Germany, Russia and the United States.
The exchange did not focus on the substance of a fourth round of UN sanctions proposed by Western powers and the six agreed to hold another conference call in the near future, the source added.
"The fact that they (the Chinese) are engaging in the process is good,", the diplomat said.
Asked about the call, China's new UN Ambassador Li Baodong would only say his country, which maintains close energy and economic ties with Tehran, has always been advocating diplomacy and was "working with other members to find a peaceful solution."
The UN Security Council has already slapped three rounds of sanctions on the Islamic Republic over its refusal to halt uranium enrichment, which the West and Israel view as a cover to build nuclear weapons.
Iran denies the charges and maintains that its nuclear program is solely geared toward electricity generation for its growing population.
The new sanctions proposed by Western powers would target Iran's powerful Revolutionary Guards.
