An unknown man entered the grounds of the synagogue on Albert Street in East Melbourne at 8pm yesterday.
He poured flammable liquid on the front door of the religious building and set it alight before fleeing, Victoria Police said.
There were 20 people inside the synagogue at the time, however, everyone was able to evacuate from the back.
Fire crews were able to extinguish the blaze, which was contained to the front entrance.
Investigators are working to find a motive for the attack.
In a separate incident, a group of 20 protestors allegedly stormed and trashed an Israeli restaurant on Hardware Street in Melbourne’s CBD.
Witnesses say the group was chanting “death to the IDF” before they arrived at the restaurant called Miznon.
Diners were fearful as the group threw food and chairs at windows and knocked over tables.
It’s understood the incident took place about the same time as the fire.
Police have not linked the two.