Germany, one of the six powers negotiating with Iran on the nuclear issue, gave its voice to the pressure.
"The persistent defiance ... of United Nations resolutions and Tehran's continuation of a dangerous nuclear policy are forcing the international community to pursue further comprehensive sanctions in New York against the regime in Tehran," government spokesman Ulrich Wilhelm said on Friday.
The UN nuclear watchdog said on Thursday it feared Iran may be working now to develop a nuclear-armed missile, and Washington warned Tehran of the "consequences" of ignoring international demands.
Meanwhile, France, the current president of the UN Security Council, on Friday urged world powers to act with "determination" against Iran's atomic activities, following the report.
"This report confirms precisely the very serious concerns of the international community" over Iran's nuclear program, French foreign ministry spokesman Bernard Valero told reporters.
"It shows how urgent it is to act with determination to respond to Iran's lack of cooperation."
Key powers have long suspected that Iran's uranium-enrichment program is aimed at making a nuclear weapon. Iran insists that it only wants to use atomic power for civilian purposes.
Earlier, Russia said Iran must cooperate more actively with the UN nuclear agency to convince the world its nuclear program is peaceful, and gave fresh signals the Kremlin may back sanctions.
"Tehran must be more active in its cooperation with the IAEA and widen it," Russian Foreign Ministry spokesman Andrei Nesterenko was quoted as saying at a briefing in Moscow.
The comments reinforced indications that Moscow's patience with Tehran is wearing thin, as the United States leads a push for the UN Security Council to impose a fourth round of sanctions.
But Supreme Leader Ayatollah Ali Khamenei on Friday repeated Iran's insistence that suspicions about its nuclear program were baseless. But the US-led campaign for more sanctions against Tehran appeared to be gaining ground.
Reuters and AFP contributed to this report