The conviction on espionage and anti-Iranian propaganda charges imposed on 39-year-old US reporter Jason Rezaian in October is not yet legally binding, Prosecutor General Gholam-Hossein Mohseni-Ejei said on Sunday.
"Therefore the sentencing cannot yet be carried out," Mohseni-Ejei said in remarks carried by Fars news agency.
Rezaian, the Washington Post's Iran correspondent, is alleged to have passed on information to the White House through a US journalist. He denies the charges, saying he was merely carrying our his duties as a journalist in Iran.
Mohseni-Ejei said the United States had proposed a prisoner swap for Rezaian, but he did not say whether Iran would accept such a move.
It is believed that Rezaian will be given a prison sentence, but neither his lawyer not the journalist himself have received notification of this.
The US has described the charges as absurd and has demanded Rezaian's immediate release.