The Reds have already spent £89m on Adam Lallana, Dejan Lovren, Lazar Markovic, Emre Can, Divock Origi and Rickie Lambert, having sold striker Luis Suarez to Barcelona for £75m.
"We still have some positions that we want to fill within the squad so that by the end of August we have a strong group of players to go forward with," he said.
"We've still got some business to do. We've brought in specific players for specific roles, players that have the profile of how we work.
"A lot of the players that have come in, the transition has been very smooth and that should make the adjustment that bit easier.
"Of course some of them are young and coming to a different country, like Emre Can. That will take a little bit of time. The players are transitioning very well, though it will take a little bit of time."