The situation with Iran is "in flux" because the US has sent a large fleet to the region, Trump said in an interview with the news portal Axios.
"We have a big armada next to Iran. Bigger than Venezuela," he told the portal, adding that diplomacy remained on the table.
"They want to make a deal. I know so. They called on numerous occasions. They want to talk," he told Axios.
On Monday, the US military's Central Command (CENTCOM) said a fleet of warships including the USS Abraham Lincoln had arrived in its area of responsibility, which covers the Middle East and includes Iran.
The aircraft carrier battle group is currently deployed in the Middle East "to promote regional security and stability," CENTCOM said.
The ship is currently in the Indian Ocean. No further details on its position were provided.
Trump recently refused to rule out military intervention by the US in Iran following a violent crackdown on protests which, according to rights groups and witnesses, resulted in thousands of deaths.
Axios cited unnamed sources as saying Trump hasn't made a final decision about a potential military escalation in the region.
The portal reported Trump may be presented with additional military options from his security advisers this week.
The USS Abraham Lincoln and accompanying warships give Trump additional offensive and defensive options should he decide to attack Iran, the Wall Street Journal reported.
