Kiwis in Bali should stay at least 12km from the Mount Agung volcano as the alert level is raised to its highest point.
There's been unprecedented seismic activity around the volcano, a sign that an eruption could be imminent.
Indonesia's National Disaster Management Authority raised alerts for the volcano to level four, the highest point on its scale.
Foreign Minister Gerry Brownlee says New Zealanders in and travelling to Bali should register with Safe Travel.
There are already 386 Kiwis recorded on the island.
"Residents and tourists have been warned to stay at least 12km from the volcano's crater," he said.
"There are evacuation orders in place for those within that area due to the potential for an eruption."
Brownlee said should a volcanic ash cloud form, New Zealanders should confirm travel arrangements with airlines or travel agents prior to arriving at airports.
The volcano is situated about 70km from the main tourist area of Kuta but is close to another resort area, Kubu.