Police are hunting an arsonist who set fire to a Melbourne synagogue with more than a dozen people, including children, inside.

The 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.

An unknown man entered the grounds of the synagogue on Albert Street in East Melbourne at 8pm yesterday.An unknown man entered the grounds of the synagogue on Albert St. He poured flammable liquid on the front door of the religious building and set it alight before fleeing, Victoria Police said. (Nine)

There were 20 people, including children, having a Shabbat dinner 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.

Victoria Police Commander Zorka Dunstan said the arson was being treated very seriously, but it had not been declared a terrorist attack.

Victoria Police have released images of a person they wish to speak to in relation to the suspicious fire at an East Melbourne synagogueVictoria Police have released images of a person they wish to speak to in relation to the suspicious fire at an East Melbourne synagogue (Supplied)

“This was clearly a targeted fire and we will not accept any acts of anti-Semitism or hate-based crime,” Dunstan said.

Police have released a CCTV image of a man they wish to speak to in relation to the fire.

He is described as being of Caucasian descent, and aged in his mid-30s. He has a beard and long hair, and was seen wearing dark clothing.

Jenny and Danny were two of the group inside when the fire was started.

“It’s beyond belief and I just feel that it’s un-Australian,” Danny said.

Jenny and Danny were two of more than a dozen people inside the synagogue.Jenny and Danny were two of more than a dozen people inside the synagogue. (9News)

Dr Dvir Abramovich from the Anti-Defamation Commission also spoke out about the incident.

“We don’t have to wait for somebody to be killed or injured to take this threat seriously,” Abramovich said.

Police said at this stage the man’s motive is unclear.

“We are not declaring this a terrorist incident; we will determine the intent of the persons involved to determine if it is terrorism,” Dunstan said.

Police investigate two separate incidents

In a separate incident, a group of 20 protestors 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. 

One 28-year-old was arrested at the time and has been released, and a further investigation will follow to identify the alleged offenders.

Dunstan said the small group had peeled away from a larger protest in the CBD.

Israeli restaurant was also targeted In a separate incident, a group of 20 protestors allegedly stormed and trashed an Israeli restaurant in Melbourne’s CBD on Hardware Street. (Nine)

Victoria Police also revealed a third incident took place this morning, but they have not linked the three separate attacks – it is not clear whether the third attack was an anti-Semitic motivated attack.

In the third incident, a group of men entered the premises of a business on Para Road in Greensborough at 4.30am.

Three cars were torched and spray paint was used to vandalise vehicles and a wall of the business, which is known to manufacture parts for military planes.

Police said they have not confirmed an anti-Semitic motive for the attack on the business; however, Dunstan said they alerted the press to the incident because they had “been subject to pro-Palestinian activity” in the last 12 months.

She clarified there were no previous criminal attacks on the building, but rather protest activity surrounding the business. 

“Investigators across all three incidents are liaising with counter terrorism to understand if there are any links,” Dunstan said.

“At this stage we are not aware of any links, but we are not discounting it.”

Police have not linked the two.

Executive Council of Australian Jewry co-chief executive Alex Ryvchin called the attacks “a severe escalation directed towards our community”.

“We urge all sides of politics and all Australians to condemn these deplorable crimes,” he said in a statement.

“Those who chant for death are not peace activists.

“Those who would burn houses of prayer with families inside do not seek an end to war.

“Those responsible cannot be reasoned with or appeased.

“They must be confronted with the full force of the law.”

Melbourne's Lord Mayor Nicholas Reece called the arson attack "shocking." Melbourne’s Lord Mayor Nicholas Reece called the arson attack “shocking.” (Nine)

Melbourne’s Lord Mayor Nicholas Reece called the attack “shocking.”

”These are absolutely shocking, unspeakable acts of cowards,” Reece told Today.

“I cannot condemn this sort of behaviour in stronger terms… this is a city of peace and tolerance, and we will not stand for this.

“This goes against everything that we stand for.”

The Lord Mayor also said the group were sharing a meal when a young boy inside the synagogue alerted everyone to the fire. 

Reece said police are gathering CCTV footage of the area and he is “confident” that they will catch the offender.

“I hope that we throw the absolute book at them… this is racism, this is anti-Semitic racism,” he said.

“To target a Jewish place of faith on the Sabbath, there’s people inside having a meal, to try to burn it to the ground…is there a more despicable act that you can think of in a busy city?” 

Minister for home affairs Tony Burke said he condemned the attack on the Melbourne synagogue in the “strongest possible terms”.

“Australians have a right to feel safe from violence and bigotry,” Burke said.

Minister for multicultural affairs Dr Anne Aly joined Burke in the condemnation of attack and said all Australians have a right to safety.

“Acts of anti-Semitism violate those rights and should face the full force of the law,” Aly said.

Investigators are working to find a motive for the arson attack.