Six world powers have agreed to draft a third resolution for sanctions against Iran over its nuclear programme.
Iran has denied its nuclear work is intended to develop weapons
The UN Security Council will vote on the draft if UN and EU reports say Tehran's programme is continuing, the officials said after talks in London.
Officials from the US, Russia, China, France, Britain and Germany will meet on 19 November to assess the reports.
Iran says its programme is for peaceful purposes only and denies accusations it is trying to develop nuclear weapons.
In September, the permanent members of the Security Council agreed to delay a vote on further measures until the publication of a report in mid-November on Iran's activities by the UN nuclear watchdog, the International Atomic Energy Agency [IAEA].
At Friday's meeting, the officials agreed to ask the EU's foreign policy chief Javier Solana to hold a further meeting with Iran's chief nuclear negotiator and report back.
The officials "agreed to finalise a text for a third UN Security Council sanctions resolution with the intention of bringing it to a vote in the UN Security Council unless the November reports of Dr Solana and [IAEA head Mohammed] ElBaradei show a positive outcome of the efforts," a spokesman from the British Foreign Office said.
The US, Britain and France pushed for a third resolution earlier this year but were blocked by China and Russia.
'Years from bomb'
Iran's former President, Hashemi Rafsanjani, said on Friday that talks between his country and the IAEA were making progress.
He said dialogue should be given more time and warned that any military action against Iran "will create another quagmire for the global arrogance of the United States".
Mr ElBaradei said on Sunday that Tehran was years away from developing a bomb - a statement dismissed by the US and France.
French Defence Minister Herve Morin challenged Iran to allow UN inspectors unlimited access to sites.
US officials said Iran's efforts to enrich uranium rather than import it more cheaply, indicated that it really wanted nuclear weapons.
The IAEA has some access to Iranian nuclear facilities but Tehran's refusal to allow intrusive inspections means the UN cannot verify the absence of undeclared nuclear material.
There is tension between Western countries and Mr ElBaradei over an agreement he reached with Iran in August, drawing up a timetable for the country to answer questions about its past nuclear activities.
Mr ElBaradei says he will report to the IAEA's board in mid-November on how much information Iran has provided.