At a ceremony commemorating the 20th anniversary of the Bali bombings, graphic footage of the attacks was shown, upsetting survivors and the families of the victims.
On the Indonesian island late on Wednesday, hundreds gathered to honour the 202 victims of the attacks.
One victim’s relative said he felt “sick” when the footage aired. It is unclear who made the documentary video.
The Australian government says it is “deeply disappointed” and will formally raise concerns with Indonesia.
People from 21 countries – including 88 Australians – died in the bombings at two popular nightclubs in Kuta on 12 October 2002. Another device exploded outside the US consulate but did not cause harm.
A local group linked to al-Qaeda was blamed for what is Indonesia’s deadliest terror attack.
A 10-minute documentary-style film was screened at 23:05 local time on Wednesday – marking the moment the first bomb detonated.
It included footage of dazed and injured people fleeing in the fiery aftermath. There was also audio of people yelling and a clip from the 9/11 terror attacks in New York, the Sydney Morning Herald reported.
Australian man Jeff Marshall, whose father Bob Marshall died in Kuta’s Sari Club, said he was stunned by the decision to show such “carnage”.
“[It] just ripped all our hearts apart, seeing it all again,” he told the Australian Broadcasting Corporation.
Attendees say the video also included footage of those behind the attack, including convicted bomb-maker Umar Patek, who is currently being considered for early release on parole.
“We were expecting a minute’s silence once we got to 11:05 pm,” Jan Laczynski told Sydney radio station 2GB.
“[Instead] you had all the Bali bombers being paraded. You had the actual bomb sequences happening on the screen.”
Mr Laczynski – who lost five friends in the blasts – said some footage was so “traumatic” that he left the service.
Australia’s Department of Foreign Affairs and Trade said its government wasn’t involved in organising the event.
“We understand the distress it has caused,” it said in a statement.
Indonesian authorities have not responded.