The International Atomic Energy Agency has passed a resolution expressing deep and growing concern over Iran's nuclear programme, but stopping short of imposing any punitive measures.
The UN agency received a report last week warning that Iran had carried out activities relevant to the development of a nuclear explosive device.
Iran insists that it is enriching uranium only to use as fuel for nuclear power stations.
However, the United States, Britain, China, France, Russia and Germany believe it is trying to develop a nuclear weapon.
The BBC reports the resolution was adopted by 32 votes to two - Cuba and Ecuador.
The resolution asked Iran to clarify matters "to exclude the existence of possible military dimensions" to its nuclear programme.
Iran's IAEA envoy said the resolution would only strengthen Iran's resolve.
"It will be business as usual ... We will continue our work as before," Ali Ashgar Soltanieh said in Vienna.