"You'll be hearing about Iran very shortly," The Hill quoted Trump as saying, when asked by reporters if he will certify or decertify the Obama-era agreement.
Trump further said that Iran has not "lived up" to the spirit of the deal.
In a meeting with the military leaders, Trump emphasised that Iran must not be allowed to obtain the nuclear weapons.
"The Iranian regime supports terrorism and exports violence, bloodshed and chaos across the Middle East. That is why we must put an end to Iran's continued aggression and nuclear ambitions. They have not lived up to the spirit of their agreement," he added.
Trump has repeatedly lambasted the Joint Comprehensive Plan of Action (JCPOA) - one of the most important foreign policy legacies of his predecessor, Barack Obama - most recently at the U.N. general assembly last month.
Under the U.S. law, Trump has time till October 15 to certify that Iran is complying with the nuclear deal. If he declines to certify Iran, then the Congress will have the option to re-impose sanctions on Iran, which would effectively end the deal.
Earlier on Tuesday, the U.S. Defence Secretary James Mattis had openly contradicted Trump's position on the Iran nuclear deal, while testifying before the Congress, by backing the nuclear deal with Iran and saying it is in the interests of national security to maintain it.
During a Senate Armed Services Committee hearing on Tuesday, Mattis was asked whether he believed it was currently in the US national security interest to remain in the agreement.
After a significant pause, he replied, "Yes, senator, I do." (ANI)