The airport in Catania, Sicily's second-largest city, was closed for a while, the Italian news agency ANSA reported. It partially reopened later Thursday.
Ash fell on the city and surrounding farmland. The eruption, which was not a major one, began late Wednesday.
Organizers said the eruption will not affect Sunday's stage of the Giro d'Italia, when competitors will be bicycling on Etna's slopes, The Daily Telegraph reported. Rocks fell on some of the roads that are part of the course.
"Sunday's stage is not at risk. The stretch in question is only the last 4 miles on Etna," director Angelo Zomegnan said. "But on-site teams are already working to clear the road. We are calm."