Iran's Revolutionary Guards have shot down an Israeli spy drone that was attempting to penetrate the space surrounding Iran's Natanz nuclear enrichment site, according to a report from the country's state news agency. 

IRNA said the Revolutionary Guards had struck the drone with a ground-to-air missile when it attempted to penetrate “the nuclear off-limits area of Natanz.” 

“A spy drone of the Zionist regime was brought down by a missile... This stealth drone was trying to approach the Natanz nuclear zone,” Agence France-Presse quoted the corps as saying in a statement on its official website sepahnews.com.

"The downed aircraft was of the stealth, radar-evasive type and it intended to penetrate the off-limit nuclear area in Natanz... but was targeted by a ground-to-air missile before it managed to enter the area," said IRNA, citing the Revolutionary Guards.

Israel has not confirmed the reports, but Israeli Prime Minister Benjamin Netanyahu said on Friday that a military option was "necessary" for negotiations to be effective in getting Iran to curb its nuclear potential.

The United States and the West suspect Iran is planning to build a nuclear bomb. However, the United Nation nuclear chief appeared optimistic this week about a possible diplomatic resolution to those international concerns.