The former Schalke man missed out on Liverpool's weekend win at Brighton and Hove Albion after picking up a knock during the preceding victory over Stoke City.
And Klopp has now confirmed that Matip will be unavailable when the Reds contest their final Champions League group game against Spartak at Anfield in midweek.
However, he does not expect to be without his No.32 for too long.
"He has hurt his muscle. I don't know how long exactly he'll be out, but he's definitely not playing Wednesday," he said.
"A month? No, I don't think so. But as always, it's possible. We have to wait.
"But it's possible that it will be shorter. We will see."
Midfielders Gini Wijnaldum and Emre Can featured in a makeshift three-man backline at Brighton in the absence of Matip, impressing as Chris Hughton's team were largely kept at bay.
Klopp said of the pair: "Emre needs to do that, like Gini can do that. They have to do it, we don't have anybody else.
"I enjoyed it. It was like 'wow, interesting'. We had 20 minutes in training and then we spoke for a little bit in the team meeting before the game again about it.
"But it's not long. It was clear it wouldn't be perfect, but the boys were ready to cope with the difficulties of the new system.
"They did really well."