Washington has repeatedly called for zero enrichment, but has also sought to address Iran’s ballistic missile programme and its support for militant groups in the region – issues which Israel has pushed to include in the talks.
Western countries accuse the Islamic republic of seeking to acquire nuclear weapons.
Tehran denies having such military ambitions but insists on its right to this technology for civilian purposes.
Trump, who has ratcheted up pressure on Iran to reach an agreement, has deployed a significant naval force to the region, which he has described as an “armada”.
After sending the aircraft carrier USS Abraham Lincoln and escort battleships to the Gulf in January, he recently indicated that a second aircraft carrier, the Gerald Ford, would depart “very soon” for the Middle East.
Meanwhile, Iranian naval forces this week conducted military drills in the Gulf and around the strategic Strait of Hormuz.
Separately, the Iranian and Russian navies were conducting joint drills in the Sea of Oman and the northern Indian Ocean on Thursday.