Iran said in August it had arrested "tens of spies" in state bodies, many of whom were dual nationals.
In June, Iran said it executed a former contract employee of the defense ministry aerospace body on charges of spying for the U.S. Central Intelligence Agency.
Judiciary spokesman Gholamhossein Esmaili said an unspecified number of suspects, arrested less than a year ago, faced possible death sentences in military tribunals, state televison reported.
"Two of the defendants, who were not military, have received long prison terms," Esmaili added, without giving details.
Iran announced on Monday it had amassed more low-enriched uranium than permitted under a 2015 nuclear deal, a move denounced by President Donald Trump as "playing with fire" amid concerns about deepening U.S.-Iranian confrontation.
The initiative marked Tehran's first major shift from the provisions of the pact since the United States pulled out of it more than a year ago.However, Iranian Foreign Minister Mohammad Javad Zarif said the move was not a violation of the accord, arguing that Iran was exercising its right to respond to the U.S. walkout.