"I think it was a cheap shot and I think it was dirty," Pierce said Tuesday night of the way Toronto Argonaut linebacker Brandon Isaac rammed his helmet into his chin Saturday.
"It's not the way the game should be played and obviously I'm upset about that."
Pierce said there should have been a fine or suspension in addition to the 15-yard penalty for roughing the passer.
He said he viewed it as a deliberate attempt to injure. It took him out of the game Winnipeg lost 29-10.
"If a player goes out to attempt to injure then I think that it completely goes against the fibre of this game and what this game stands for."
Winnipeg coach Tim Burke said earlier in the day it wasn't certain whether Pierce could play Monday when the Bombers meet the Alouettes in Montreal.
"He has one more test that he has to clear before he'll be cleared to play," Burke said. "He will be evaluated tomorrow and if it goes another day he'll be evaluated after that, so however long it takes for him to pass that test is when he's able to play."
After the hit Pierce went to the dressing room but returned for a few plays before again leaving the field. He reported a headache initially that didn't go away.
Pierce said Tuesday night he now feels fine but he has to defer to the experts about when he can return to the field.
Burke said he's heard nothing from the CFL about any action against Isaac over the hit.
It was only Pierce's second game since returning from a foot injury that sidelined him July and Burke said it was naturally disappointing to see him hurt again.
"Very disappointing in the respect that he would have to take a hit like that No. 1," said Burke. "I don't know how many people would have come away from that hit without having some kind of an injury.
"Fortunately, it's a mild concussion and not anything really bad or anything like that. It's nothing that's a career-ender by any stretch of the imagination."
There have been calls for Pierce to hang up his cleats over this, his latest in a series of injuries, but Burke says that's a choice the player must make for himself.
"Career decisions are up to Buck, not up to anybody else," said Burke.
Pierce declined to discuss how many concussions he may have had in his career.
If Pierce doesn't play Monday, Burke said backup Joey Elliott will take his place.
And he said if Pierce isn't cleared to play soon, they may have to make that decision regardless.
"If it goes on towards the end of the week and he hasn't passed it (the test), there comes a point where you have to say `We're going with Joey.'"
The 3-10 Bombers have lost any but a faint statistical chance of making the CFL post-season.
Pierce said the integrity of the game is on the line when such things happen.
"There's going to be hits like this throughout the course of the season . . . I just wish it was dealt with in a timely manner," he said.
"I'm glad they assessed it as a flag but it has to be a bit stricter punishment when it comes to these things."