"Well, I have decided," Trump told reporters who pressed him for an answer before they were escorted out of his meeting with Mahmoud Abbas, president of the Palestinian Authority.
Trump, however, declined to disclose his decision, teasing to a future date.
"I'll let you know what the decision is," Trump said with a smile.
Trump has long railed against the deal President Barack Obama struck with Iran to curb the nation's nuclear ambitions. He used it as a foil against Hillary Clinton during the 2016 campaign. During his first address to the United Nations General Assembly on Tuesday he labeled the deal "one of the worst and most one-sided transactions the United States has ever entered into."
Though the Trump administration is currently mulling whether to leave the Iran deal, they have made a series of procedural steps, such as extending sanctions relief for Iran, that have kept the 2015 nuclear deal going.
Trump is expected to yet again extend the sanctions relief, a key principle of the deal that allows Iran to do business and keeps the United States in compliance with the agreement, CNN reported earlier this month
The Trump administration is wrapping up a months-long review of US policy towards Iran and Trump has hinted at a series of events that he favors leaving the deal.
"Frankly, that deal is an embarrassment to the United States, and I don't think you've heard the last of it -- believe me," Trump said on Tuesday at the United Nations.
Iranian President Hassan Rouhani told CNN on Monday
that the United States will pay a "high cost" if Trump decides to leave the deal.
"Exiting such an agreement would carry a high cost for the United States of America, and I do not believe Americans would be willing to pay such a high cost for something that will be useless for them," Rouhani told CNN's Christiane Amanpour.
Trump also urged the Palestinian and Israelis to come together to strike a peace deal during his meeting with Abbas.
"I think we have a pretty good shot," Trump said. "Maybe the best shot ever."
But Trump, while gauging the chances of a deal, added, "We will see if we can put it together. Who knows. Stranger things have happened."