A loud noise heard in the outskirts of the town of Karaj, to the west of the Iranian capital Tehran, on Wednesday was caused by a rocket fired by the Revolutionary Guards during a training exercise, Iran's official news agency IRNA reported.
Rumors of a missile explosion in the west of Tehran were earlier denied by a deputy to the governor of Tehran's province.
Karaj hosts several sensitive locations, such as the TESA centrifuge-parts workshop that was hit by apparent sabotage last June. Centrifuges can be used to enrich uranium.
"The loud noise heard this afternoon in the suburbs of Karaj was caused by the firing of a rocket during a training exercise from one of the Guards' bases, which has caused some speculations and rumors online," a spokesperson for the Guards told IRNA.
"Such exercises are not uncommon and we call upon our dear compatriots not to pay attention to the rumors made by the opponents and enemies of the Iranian nation."
Tehran is currently negotiating with major powers to revive a 2015 nuclear deal in Vienna and conducted a war game in December to send a warning to Israel, its arch-foe in the region.
Israel has long warned it will use military action if diplomacy fails to curb Iran's fast-advancing nuclear program by reviving the nuclear agreement. Iran says its nuclear ambitions are peaceful.