Iran's Fars news agency reported on Friday that explosions were heard over the city of Isfahan.
Isfahan is located some 350 kilometers south of Tehran.
The blasts were reportedly heard near its international airport. Isfahan is also home to a major Iranian military airbase.
Other Iranian media say flights have been suspended over several cities.
This comes after Israel vowed to retaliate to last weekend's Iranian drone and missile attack. But it's not clear what caused these blasts or if Israel is involved.