Oxlade-Chamberlain was carried down the tunnel on a stretcher after damaging his knee ligaments during Tuesday's Champions League semi-final first leg against Roma at Anfield.
The England international will miss the remainder of the 2017-18 campaign in addition to this summer's World Cup, and Klopp has said that Liverpool "will wait for him like a good wife when a man is in prison".
"I have no words. I cannot believe this wonderful player, in such a positive situation, something like this happened. It is such a shame. It is not fair," Klopp told reporters.
"That is how life is sometimes. If you get a lemon, make lemonade. That is what we must do. Alex is a positive person and he will be back. We will wait for him like a good wife when a man is in prison."
Liverpool are back in Premier League action at home to Stoke City this weekend before travelling to Roma for the second leg of their Champions League semi-final next week.