Lallana has struggled with various muscular injuries over the last 18 months.
The 30-year-old winger made just three starts last season, and he has managed that same number so far this campaign.
Klopp said: "Could he [Lallana] be in a better place mentally?
“Yes, if he was playing and had scored 20 goals in the last 10 games.
"But everything is fine. Adam knows that we need him."