The European Union has vowed to continue pressing Iran with sanctions over Tehran's controversial nuclear program.
They also agreed on the need to strengthen sanctions against Syrian President Bashar al-Assad's regime in response to violence in Syria.
Speaking on the second day of a two-day EU foreign ministers meeting in Cyprus, EU foreign-policy chief Catherine Ashton called on Tehran to prove its claim that Iran's uranium-enrichment program is peaceful and is not aimed at building nuclear weapons.
"I urge Iran to seriously look at the proposals that have been put forward and to engage with us to recognize, as they keep saying, they want to be clear that they do not seek a military option in terms of their nuclear program -- and to demonstrate the truly peaceful nature of that program by all that they do," Ashton said.
Ashton also said she would continue diplomatic efforts through the United Nations to ensure that Iran complies with its obligation to cooperate fully with the inspections by the UN's nuclear watchdog, the International Atomic Energy Agency.
"My job from the [UN] Security Council is to do everything I possibly can, through negotiations, to ensure that Iran complies with its obligation, and I will continue to do that," she said.
German Foreign Minister Guido Westerwelle told reporters a new global nuclear arms race would likely be the result if Tehran acquired nuclear weapons.
Italy's Foreign Minister Giulio Terzi di Sant'agata said the EU was concerned "about the security of our citizens in the face of the potential threat of a nuclear-armed Iran."
Meanwhile, after agreement by the EU's 27 foreign ministers on the need to massively strengthen humanitarian aid to Syrian civilians, Ashton said more sanctions against Assad's regime also were being considered in response to its military assaults in urban areas across the country.
"We are adamant [that Assad] should go and that we need to see the political transition to inclusive democracy, and colleagues and I were very clear about the inclusive nature of what needs to happen for the people of Syria in the future," Ashton said.
Ashton has been asked to prepare a new round of sanction measures by October.
She says a top priority for the EU is to offer its full backing to the new UN-Arab League envoy to Syria, Lakhdar Brahimi, who is set to begin mediation efforts to end the civil war.
The London-based Syrian Observatory for Human Rights says more than 26,000 people have been killed in Syria -- mostly civilians -- since Assad's regime triggered an uprising by launching a brutal crackdown against opposition demonstrators in March 2011.
With reporting by Reuters, AP, AFP, and dpa