Thursday's meeting of the council's permanent members plus Germany agreed to send the latest draft resolutions back to their governments.
They were to decide on Friday whether to distribute the text to UN Security Council members.
One source said that if there was agreement there could be a vote on the resolution next week.
Thursday's meeting went ahead despite China's anger over a "watered-down" statement on the killing of four UN peacekeepers during an Israeli attack in Lebanon on Tuesday.
Wang Guangya, China's UN ambassador, had warned that the US refusal to accept criticism of Israel in a security council statement could have a "negative impact" on other council work, including the Iran resolution.
Before the peacekeepers were killed, diplomats had reported progress in their negotiations, which have been marked by China and Russia's refusal to accept any talk of sanctions.
Diplomats said the main elements of the draft under discussion reflect a communique adopted by foreign ministers from the six countries at a meeting in Paris on July 12.
Jean-Marc de La Sabliere, the French ambassador to the UN, said on Tuesday: "One fundamental element of that agreement is to make the suspension of all enrichment-related activities mandatory, including research and development."