TEHRAN, Iran

Iran would have no choice but to acquire nuclear weapons if attacked by the United States or its allies, a senior adviser to Supreme Leader Ali Khamenei said Monday.

"We are not moving towards (nuclear) weapons, but if you make a mistake on the nuclear issue, you will force Iran to move towards that because it has to defend itself," Ali Larijani told state TV.

"Iran does not want to do this, but when you apply pressure...(it) will have no choice," he added.

His remarks came after US President Donald Trump threatened Iran on Sunday with unprecedented bombing if it did not agree to engage with Washington in negotiations over its nuclear program, marking the most explicit warning of military action since he assumed office in January.

"If they don't make a deal, there will be bombing. It will be bombing the likes of which they have never seen before," Trump said during an interview with NBC News.

In his first response to Trump, Khamenei warned that any “external aggression” would be met with “firm retaliation.”

Larijani said the US will force Iran to make "different" decisions if it chooses to bomb Iran by itself or through Israel.

"Iran does not want to take this path, but when you apply pressure, it finds a secondary justification and has no other choice. The people will push for it, arguing that it is necessary for the country’s security,” he added.