President Donald Trump issued a warning to Iran if it fails to reach an agreement with the U.S. regarding its nuclear program.  I

"If they don't make a deal, there will be bombing," he said on Sunday during an interview with NBC News. 

He also signaled he would take further economic measures if necessary.

"But there's a chance that if they don't make a deal, that I will do secondary tariffs on them like I did four years ago," he said. 

Iran has rejected direct negotiations with the U.S. over its nuclear ambitions.