UN leader Ban Ki-moon called for "peaceful" efforts to ease tensions between Iran and Western nations but stressed that Iran must prove its nuclear program is not aimed at producing weapons.
The West's showdown with Iran has heightened in recent days with Tehran issuing threats and warning the US not to send one of its aircraft carriers through the strategic Strait of Hormuz.
Both sides must "do their best to first of all defuse the tension in the region, and try to resolve all issues, differences of opinion, through dialogue, in peaceful means," Ban told reporters at a New Year meeting Friday.
"At the same time Iran should fully comply with the relevant resolutions of the Security Council," he added. The UN Security Council has passed four rounds of sanctions against Iran calling on it to end uranium enrichment.
The UN secretary general said he remained concerned by a report released by the International Atomic Energy Authority in December which highlighted a probable military dimension to the nuclear drive.
The United States and European powers say that Iran is seeking a nuclear bomb capability. Iran insists it wants nuclear energy for peaceful purposes.
Ban said he was "very much concerned" by the IAEA report released in November.
"It is the responsibility of the Iranian authorities to prove that their nuclear program is for genuinely peaceful purposes. But the international community seems to be not convinced," Ban said.
"I urge the Iranian government to try to prove the nature of their nuclear program," he added.