The police were called to the Prosecco Lounge bar on King George Road at 12.15am on Sunday 18 June, after receiving a report that a brick and a petrol bomb were thrown through the window.
The bar, previously called the White Ensign, was closed when the arson attack took place and nobody was inside.
Object burnt out
Detective inspector Sean McGuigan, from Northumbria police, said: “A full investigation is ongoing to identify those responsible for this arson but we do need anyone with information to get in touch.
“Thankfully, nobody was in the premises at the time so there were no injuries.”
McGuigan said the object burnt out “very quickly” and so there was only minor damage.
McGuigan continued: “The owners are obviously quite shaken by this unprovoked incident and we are now working with them to try and establish reasons why they may have been targeted.”
Extra patrols are being carried out in the area as the police conduct their investigation.
Police are appealing for anyone who saw anyone acting suspiciously in the area around the time of the arson to call police on 101.