But the text, proposed at the International Atomic Energy Agency by the five permanent members of the UN Security Council, Germany and 12 others, stops short of reporting Iran to New York or setting Tehran a deadline to comply.
With a simple majority of the IAEA's 35-nation board of governors already on board, the resolution, saying it was "essential for Iran and the Agency to intensify their dialogue," was expected to be approved later Friday.
"There is a very large majority of countries who would like the resolution to be adopted by consensus," negating even the need for a vote, one European diplomat told AFP on Friday.
The resolution calls on Iran to comply "without delay with its obligations" and appeals to Tehran "to engage seriously and without preconditions in talks aimed at restoring international confidence."
But to assuage Chinese and Russian misgivings, it sets no deadline for Iran, requesting instead IAEA head Yukiya Amano to report to the watchdog's board in March on Tehran's "implementation of this resolution."
Amano said on Thursday he had written to Iran on November 2 proposing a "high-level" visit to Tehran, saying "clarifying all outstanding issues was in the interests of Iran, and other countries."
"It is clear that Iran has a case to answer," he told reporters.
Last week, the IAEA came the closest yet to accusing Iran outright of seeking to develop nuclear weapons, in a report immediately rejected by the Islamic republic as "baseless."
Iranian Foreign Minister Ali Akbar Salehi said on Wednesday that Tehran would send "an analytical letter with logical and rational responses" to the IAEA.
Iran's mission in Vienna meanwhile released a November 16 letter to Amano, saying his "leaking" of names of Iranian scientists made them "targets for assassination" by "terrorist" groups and the US and Israeli secret services.
The report laid bare deep differences within the so-called P5+1 bloc dealing with the Iran question, the five permanent members of the UN Security Council -- the United States, China, Russia, Britain, France -- and Germany.
Washington, Paris and London jumped on the IAEA report as justification to increase pressure on Iran, already under four rounds of Security Council sanctions and additional US and European Union restrictions.
But Beijing, which relies heavily on Iranian oil imports, and Moscow, which also has close commercial ties and built Iran's only nuclear power plant, have been more cautious.
Israel's ambassador on Thursday expressed disappointment at the resolution, having hoped for a stronger response and even what would be a fifth round of sanctions.
"It could be tougher," Israel's envoy Ehud Azoulay told AFP on the sidelines of the meeting at the IAEA's Vienna headquarters.
But Western diplomats stressed all major powers had agreed, thus avoiding what would have been a potentially damaging split in the UN Security Council, where relations have already been tested this year over Libya and Syria.
"It is good we have a resolution supported by the six (powers)," the European envoy said. "It supports the work of the agency, condemns the lack of Iranian cooperation and calls on Iran to cooperate at last and without delay."
Mark Hibbs from the Carnegie Endowment for International Peace think tank said the resolution "goes far to accommodate the interest in China and Russia -- and Iran -- in resolving outstanding issues diplomatically."
He noted it calls on Iran to address outstanding "substantive issues" but does not single out weapons-related items in Amano's report, "and, most significantly, it doesn't set any deadline for Iran to comply."