The national disaster agency said the eruption lasted four minutes and 30 seconds and spread lava and incandescent rocks about 3 kilometres from the crater.
Nine villages experienced thick ash fall, but the agency said it was not raising the alert level for the volcano and its exclusion zone remained a 4-kilometre radius around the crater.
The Directorate General of Air Transportation said four flights to Bali were diverted and five flights out of the popular tourist destination were cancelled because of volcanic ash.
One Jetstar and two Virgin flights into Sydney were delayed because of the ash.
The Virgin flights, due in early this morning, are now expected to arrive at 10:00pm.
Flights departing from Sydney for Bali’s Denpasar Airport are scheduled to leave on time at this stage.
Mt Agung became active again in 2017 after more than a half century of slumber following a major eruption in 1963.
Eruptions last year played havoc with flights, disrupting travel for tens of thousands. In July, one eruption ejected a 2,000-metre column of ash into the air and hurled lava down the volcano’s slopes.