In case of urgent support, Vietnamese citizens can contact the embassy’s hot line at 62811161025.
Thousands of tourists are being stuck in Bali as many flights have been cancelled due to the volcano’s eruption.
A report from local aviation navigation authorities showed that "aircraft flight channels are covered with volcanic ash", Indonesia's transportation ministry said.
Denpansar airport, about 60 km (37 miles) from the volcano, will be closed until 7 a.m. local time on November 29, it said.
Ten alternative airports have been prepared for airlines to divert inbound flights, including in neighbouring provinces.
Agung rises majestically over eastern Bali to a height of just over 3,000 metres (9,800 feet).
On November 27, authorities ordered 100,000 residents living near the volcano to evacuate immediately, warning that the first major eruption in 54 years could be "imminent". An 8-10 km exclusion zone has been imposed around the summit.
Agung's last eruption in 1963 killed more than 1,000 people and razed several villages by hurling out pyroclastic material, hot ash, lava and lahar. The mount experienced unprecedented levels of seismic activity in September, resulting in the evacuation of 140,000 local residents.
Mount Agung is one of more than 120 active volcanoes extending the length of Indonesia, which straddles the Pacific Ring of Fire.