The Reds missed out on the opportunity to secure progression to the knockout stages of the Champions League as they drew 3-3 against the Spanish side, having led 3-0 at half time.
Spaniard Moreno conceded a free kick and a penalty in the second half, from which Sevilla scored two of their comeback goals.
"What [Moreno]'s doing for the penalty, you wouldn't see a child doing it," Keane told ITV Sport. "It's pure madness for an international player to do that.
"You look at the free-kick he gave away, that's nothing to do with the manager. This has nothing to do with team shape or mentality. I know it's a team game, but sometimes you have to point the finger and say, 'you're killing us, you're costing us'.
"Liverpool will win a lot of football matches, but when it comes to the big games they're going to come up short because they've got a couple of defenders who just aren't good enough and they'll always get found out."