"We've had some very, very good talks with Iran and I don't know if I'll be telling you anything good or bad over the next two days, but I have a feeling I might be telling you something good," he told reporters on Sunday before boarding Air Force One in New Jersey.
Trump, who has repeatedly warned Tehran of military action if diplomacy fails, said he still hoped a deal could be reached to avert further escalation.
"I'd love that to happen because I'd love to see no bombs dropped and a lot of people dead," he added.
The US accuses Iran of seeking nuclear weapons - a claim Tehran denies, insisting its nuclear activities are solely for civilian purposes.
Talks are being mediated by Oman, whose Foreign Minister Badr al-Busaidi said on X that there had been "some but not conclusive progress" in the fifth round of negotiations on Friday.
"We hope to clarify the remaining issues in the coming days," he added.
It remains unclear when the parties will meet again.
Washington wants Tehran to halt uranium enrichment entirely, viewing it as vital to preventing Iran from developing nuclear weapons.
Tehran has rejected that demand but has signalled willingness to limit its program and accept stricter inspections.
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