The defending champions, who have drawn four league matches in a row, were booed by their own fans at the end of the game.
Florian Wirtz gave Liverpool the lead in the first half - 10 minutes after Dominik Szoboszlai missed a penalty - but Marcus Edwards scored a second-half equaliser.
"Frustration is the word which is definitely in my head," said Van Dijk.
"After 60 minutes, we started to become sloppy and it's not the first time. We have to address that. It's been spoken about already but we have to address it again apparently.
"We have another 48 hours to assess it, ourselves and the staff, and we will debrief and then we have to act.
"I'd say there is something lacking at the moment and we want to change that."
This is the first season since 1980-81 that Liverpool have failed to beat any of the promoted sides at Anfield. They are seven points behind third-placed Aston Villa, who have a game in hand.
"That's the reality and we need support," Van Dijk added. "I don't like boos from my own fans."
