The Reds missed out on top defensive target Virgil van Dijk during the summer after being scared off making a formal bid by Southampton.
A series of defensive issues came back to haunt Liverpool once again in their 2-2 draw with Sevilla on Wednesday night, but Klopp is adamant that the transfer market alone cannot come to his help.
"I know you are always looking for this thing - the defence was always something being talked about: 'We didn't sign this or that'," he told reporters. "If these problems could be solved by one player, you can imagine we would have put all our money into it and say: 'Let's do this'.
"It is about being dominant and losing a bit of a grip on the game in all the defensive moments. There is space for improvement. We need to learn to be dominant and not give easy goals. It is not a general defending problem but we have to improve 100%.
"It is disappointment, frustration, but that is completely normal. We are responsible for the very good parts in the game and also the not-so-good parts so you have to feel disappointed after a game like this."