Wijnaldum was expected to start during the fixture at Wembley Stadium, however he was surprisingly not named in Liverpool's match day squad.
"Gini got a knock on his knee yesterday. It's nothing serious but very painful," Klopp said.
"We couldn't do it overnight. It's not a big thing but the time was too short from yesterday to today, so he's not even involved in the squad."
Meanwhile the result leaves Klopp's side in ninth position on the League standings with 13 points.
They are already 12 points adrift of Manchester City who are at the top of the standings and they will now be aware that they are not realistically title contenders this season.