Before the game, Parker confirmed Hannibal was fit but he had chosen to leave out the Tunisia midfielder to protect him from the spotlight.
Parker told BBC iPlayer before kick-off: “As I said earlier in the week in the press conference, fundamentally I need to protect Hannibal and making sure of the right decision.
“It has been a tough decision and we come here a bit weakened today because Hannibal is a vitally important member of this squad, and I felt it was the best decision for Hannibal.
“I wouldn’t want to put him in a situation here, so we have made the decision for the best for Hannibal. That is why he is not in the matchday squad.”
Asked whether the decision was made after speaking with Hannibal, Parker said: “It was mainly my decision. Hannibal was selectable today but he is a young boy that experienced something here only a few weeks ago and I just made that decision to keep him out of here and we have another game on Tuesday.”
Hannibal was the target of chants from the Preston supporters during the game at Deepdale, with Parker describing them as “sad” and illustrative of why he had not picked the player.
The Football Association (FA) is currently investigating the incident between Osmajic and Hannibal. If found guilty, Osmajic faces a minimum ban of six games.
Parker said of the investigation: “It probably is taking a bit of time. It is a serious allegation with a lot of investigating that needs to go on.”
Preston manager Paul Heckingbottom said he had picked Osmajic after talks with the player.
“If he wouldn’t have been up for it [he would have been left out],” Heckingbottom said after the game.
“He was fine – he wanted to be involved. We discussed possible things that could happen.”
