Everton fell to a 3-1 loss, but made a number of strong challenges in an attempt to throw Liverpool off balance, with Ross Barkley's tackle on Dejan Lovren in particular standing out.
The England international received his fair share of criticism for the challenge after the final whistle and Wijnaldum feels several tackles were unacceptable and should have resulted in a red card.
"The tackles, especially those from the players from Everton made on our players, it was hard to see, hard to accept, because I think you can play the game really hard, but not with the intention to give someone an injury," Wijnaldum told Sky Sports.
"For me, my opinion, that is a bad thing, because you have to play the game fair. Of course you can play hard, to win, but not to injure the player, because that is not part of the game.
"I saw a few, even in the replay, I saw a few tackles that had to be red."