Iran's deputy foreign minister Kazem Gharibabadi warned of a wider escalation if his country was attacked, after US President Donald Trump raised the threat of strikes.
"We call upon all nations committed to peace and justice to take meaningful steps to prevent further escalation," Gharibabadi said at the Conference on Disarmament in Geneva.
"The consequences of any renewed aggression wouldn't remain confined to one country - and responsibility would rest with those who initiate or support such actions."
Iranian and US negotiators held indirect talks in Geneva last week on Tehran's nuclear programme, hosted by Oman.
A fresh round of talks in the Swiss city this Thursday has been confirmed by Muscat, though not by Washington.
It was reported earlier that Trump is planning a "limited attack" on Iran in the immediate future if Tehran does not give in to Washington's nuclear programme demands.
The New York Times said Trump is "leaning toward conducting an initial strike" to demonstrate to Iran’s leaders that they must be willing to agree to give up the ability to make a nuclear weapon.
If Tehran refuses to submit to Trump's demands, he could give the green light to a possible military assault later this year intended to help topple Iran's Supreme Leader Ayatollah Ali Khamenei.