The semiofficial Mehr news agency quoted Abbas Jafari Dowlatabadi, Tehran's chief prosecutor, as saying, "The spy has been sentenced to death ... (His) identity will be announced after approval of the verdict" by Iran's Supreme Court. He did not say when that would be.
Dowlatabadi said three more cases of espionage were under review by the Iranian judiciary. He did not elaborate.
Israel had no immediate comment.
Iran and Israel have been enemies since the 1979 Islamic revolution in Iran, and Tehran periodically announces arrest of people suspected of spying for Israel.
In 2008, Iran executed Ali Ashtari, an electronics salesman convicted of relaying information on the country's nuclear program and other sensitive data to Israel's Mossad intelligence agency.
A court in 2000 convicted 10 Iranian Jews of spying for Israel in a closed-door trial and sentenced them to prison terms ranging from four to 13 years. All were released before serving out their full sentences after international pressure.
The report on the latest death sentence came as Israel continued to press for curtailment of Iran's nuclear program.
Israel, the United States and many Western countries contend that Iran's nuclear program is intended to produce nuclear weapons. Iran denies that, saying its program is for peaceful purposes, such as generating power.
Israel considers Iran a strategic threat because of its nuclear program and missiles. Israel has said it prefers to resolve the issue through diplomatic means but has not taken a military operation off the table.
In 1981, an Israeli air attack destroyed an unfinished nuclear reactor in Iraq. Israel is also assumed responsible for an air strike on a suspected nuclear facility in Syria in September 2007.