Mount Agung spewed smoke and ash as high as 4,000 metres (13,123 feet) today morning, causing at least 28 departing or arriving flights to be delayed or cancelled, said a spokesman for Bali's airport.
Indonesia's volcanology centre has put out a red alert warning airlines of a possible eruption, with a likely significant emission of ash into the atmosphere. But as of Sunday afternoon Bali's Ngurah Rai airport was still open.
The decision to delay or divert flight was up to individual airlines, said airport spokesman Arie Ahsanurrohim.
"We try to make the airport as comfortable as possible for the passengers affected. So far we have provided special rooms for them to unpack their luggage and video entertainment so they can relax a bit," Mr Ahsanurrohim told AFP.
At least 2,000 passengers are affected by the flight disruption, mostly tourists from Australia.
"I am meant to be at work tomorrow. How am I going to pay my bills?" said Sydney-based tourist Jake Vidler.
Several domestic flights have also been cancelled such as to the nearby island of Lombok, also a popular tourist destination east of Bali. The wind has blown Mount Agung's ash in that direction.
"I've received a refund from my airline. Now I'm trying to go to Lombok by boat, hopefully the harbour is open," said Ismono, who like many Indonesians goes by one name.
It rumbled back to life in September and authorities raise the alert to the highest level, forcing 140,000 people living nearby to evacuate.
The volcano's activity decreased in late October and many people returned to their home as the alert was lowered to the second-highest level.
But Mount Agung rumbled again last Tuesday, forcing 25,000 people to seek shelter. Authorities urged people living within 7.5 kilometres (4.5 miles) of the mountain to evacuate.
The mountain spewed smoke and ash on Saturday for the second time in a week in what volcanologists call a phreatic eruption -- one which is caused by the heating and expansion of groundwater.
Authorities have decided not to raise the alert back to the highest level yet.
"This time the tremors and quakes caused by the volcano's activities are significantly less than in September," said the head of Indonesia's volcanology centre Kasbani.
Mount Agung is one of more than 120 active volcanoes extending the length of Indonesia, which straddles the Pacific Ring of Fire.