They were arrested in a province on the border with Turkey and Iraq, the state-controlled Fars news agency reported on Sunday.
The 20 are accused of sending information to Israel, including military sites.
In recent days, hundreds of people have been arrested across Iran in widespread raids on suspicion of close ties to Israel and the United States, according to local Iranian media. Among them, one person was arrested for using Starlink to send information to the London-based television channel Iran International. The country has shut down the internet during the war.
The hardline regime has also recently warned that demonstrators will be seen "as the enemy."
