Trump, who is holding a series of meetings on the sidelines with world leaders, including Japan's Shinzo Abe and India's Narendra Modi, said he saw U.S. trade prospects improving.
But Trump later left the door open for talks, saying that Iran should speak to the United States "peaceably" to ease tensions and potentially lift U.S. economic sanctions.
Prior to the Japanese leader's departure from Tokyo's Haneda airport, Abe said he wanted to exchange candid views while in Iran and help ease rising tensions.
The Trump administration informed congressional committees that it will go ahead with 22 military sales to the Saudis, United Arab Emirates and Jordan.