Police say there were about 30 people in Chops Resto Bar shortly after midnight when a Molotov cocktail was thrown through the window.
No one was injured and the suspects ran away.
A nearby residence was targeted a night earlier and a kosher cafe was hit the night before that.
Investigators are looking into a possible connection between the firebombings.
Federal Immigration Minister Jason Kenney and Liberal MP Bob Rae took to Twitter to condemn the attacks.