Winnipeg offensive linemen Steve Morley and Justin Sorensen as well as defensive back Jovon Johnson were also fined by the league for their actions as a result of the hit on Pierce.
Isaac was fined for using his helmet to hit Pierce in the chin in the first quarter of the contest and received a 15-yard roughing the passer penalty on the play.
Pierce left the game briefly before returning, but missed the second half due to a headache.
Pierce was later diagnosed with mild concussion and his status for Winnipeg's game Monday against Montreal remains up in the air.
Morley and Sorensen were both fined for separate hits on Isaac following the hit of Pierce.
Johnson was fined for making public comments that were critical of the Argonauts.
The amount of Johnson's fine wasn't disclosed but the CFL's outstanding player last year said on his Twitter account that the league had slapped him with a $300 penalty for comments that were taken out of context.
"I was fined $300.00 by the league for saying that in two years Chris Jones defenses have taken shots on our QB to take him out (BUCK) SMFH,'' Johnson tweeted in reference to Argos defensive co-ordinator Chris Jones, who had the same job last year with Calgary.
"It's crazy how in this league I can get fined by what the media writes that I said and now what I actually said SMFH. Somehow it went to I stated Chris Jones preaches to his players to take Buck out! Where in the hell does that come from the first statement?''