Matip, 32, was forced off in the 70th minute against Fulham last Sunday, his 150th Premier League game for the club, and scans have since confirmed the defender has ruptured his ACL and will require surgery.
But The Reds are unlikely to recruit in January as the club doesn't have 'endless money'.
Klopp said: "You always talk about transfers like it is the easiest thing in the world. Just bring in a player, find the money for it, as if we have endless money. I really don’t understand it. Everybody, you, the fans, everyone talks about it.
"They all cost money. It has to be the right player. Tell me a club who wants to sell a top, top centre-half who could play for Liverpool? Why should we start that process? We’ve only known for a few days that Joel will be out for a long time, which is really bad for us. We still have four centre-halves which is absolutely alright.
"If we’d had a fifth one already in before that, then it would have been a completely different team dynamic. He wouldn’t have been involved and we wouldn’t have seen steps with him or him.
"It was perfect. Is it perfect now? I’d say as long as we can go with this four then yes. If not then it will be a bit more tricky with the amount of games coming up.
"It was never wonderland where you bring in a world-class centre-half until the other is fit again. Other clubs don’t put them under the Christmas tree for us and say: ‘Take it and use it as long as you need it.’
"I didn’t really think about it (buying a centre-back in January). I don’t think so to be honest.”
Matip, who signed from Schalke in 2016, is out of contract at the end of the season.
Klopp is keen to extend his current deal but the decision is out of his hands.
He said: "I’m pretty sure the club will show their class, as you should do it. I’m pretty sure the club told Joel already that, whatever happens, as long as he is injured everything is fine.
"Now we have to make the decision together with Joel, how it looks after that. That’s a normal thing to do but he deserves all the support from us and he will get it.
"I would say so (there's a chance of a new deal) but it's not my decision."
Alexis Mac Allister and Alisson update
Alisson, who suffered a hamstring strain at the end of November, took part in training on Thursday and could return to the squad this weekend.
Klopp said: "Alisson looks good, I don't know if good enough now for tomorrow. I have to check that with the coaches and the medical department, and with Ali, of course.
"Macca doesn't look good, so we have to see day by day. They were pretty hopeful after the game that it was not serious. It's not that serious but in the period of the year if you are out for five days, it's 12 games pretty much.
"We have to wait there how he shows up here today. I don't expect him to be ready for tomorrow, I don't know about Thursday or Sunday after that, so it's pretty much stop and go. We have to see.
"Yesterday he trained normal (Alisson)."