The governing board of the International Atomic Energy Agency (IAEA) begins meeting on Monday.
The main issue will be a joint EU-US plan to refer Tehran to the UN Security Council, which could lead to economic sanctions, due to fears Iran is developing atomic weapons.
"Everything points in the direction of the need for more time. So it would be in everybody's favour to give it some three or four weeks," a senior diplomat close to the UN atomic watchdog said on condition of anonymity on Wednesday.
The European Union's France, Britain and Germany joined forces with Washington to back a Council referral after Tehran resumed sensitive nuclear activities at its Isfahan uranium processing plant last month.
Work at the plant had been suspended under a November deal with the EU.
Iran denies wanting atom bombs and says the West is trying to deprive it of its right to a full nuclear energy programme.
IAEA to set deadline
The diplomat said IAEA chief Mohamed ElBaradei suggested to US Secretary of State Condoleezza Rice that the IAEA's governing board could instead set a deadline for Iran to resume a suspension of sensitive atomic activities.
Tehran could also be set a deadline to help the UN resolve outstanding questions about its nuclear programme.
"It would be an [IAEA board] resolution that would call on Iran to not only go back to full suspension but to provide the transparency and cooperation requested by ElBaradei.
"It would have to have a deadline," the diplomat said.
"It is clear that everybody is looking for a solution that would avoid confrontation. This would give the time needed to arrive at a package solution," the diplomat added.