WSJ says it was Israel.
“Israel Strikes Iran Amid New International Push to Contain Tehran“
“Israeli, American officials discuss new ways to combat Iranian operations“
“Israel carried out a clandestine drone strike targeting a defense compound in Iran, as the U.S. and Israel look for new ways to contain Tehran’s nuclear and military ambitions, according to U.S. officials and people familiar with the operation.
Iranian officials said that the country had thwarted an attempted attack by three small quadcopters targeting a munitions factory in the city of Isfahan, right next to a site belonging to the Iran Space Research Center, which has been sanctioned by the U.S. for its work on Iran’s ballistic-missile program.
Iran said its air defenses brought down one of the drones while the two others exploded above the warehouse, causing minor damage to the roof.“
“no apparent damage to that building in Isfahan visible on Sentinel-2 image”
https://twitter.com/obretix/status/1619683458523230211