Kassian and Cernak were tangled up late in the first period of Edmonton's 3-1 loss in Tampa on Thursday when Kassian pushed his right leg out into Cernak's chest. Cernak was not injured on the play.
The Oilers argued that Kassian's kick on Thursday was not forceful.
"While we agree with Kassian that this play is not malicious, any player that intentionally uses the blade of his skate to contact an opponent, no matter the amount of force used, is putting his opponent in immediate risk of serious injury," the NHL said in its ruling.
Kassian will also forfeit $166,000 of his salary with the money going towards an emergency fund set up for the players.