The latest incident happened at around 4 a.m. this morning at Chops, a kosher steakhouse and sushi bar on Queen Mary Road near the Snowdon metro station.
"They broke the front window [and] the device was set on fire," said Const.Daniel Lacoursière of the Montreal police.
He said the suspects then launched the incendiary device through that broken window.
"It was rapidly extinguished by the sprinkler in the restaurant, so principally the restaurant was damaged by water."
Witnesses reported seeing two suspects wearing balaclavas running from the scene.
Police have made no arrests.
Yesterday morning, arsonists armed with Molotov cocktails targeted two bars in Mile-End.
The damage in those two incidents was minor.