Klopp's men sit top of the Bundesliga after their first six games, with their only dropped points in the league coming from a 1-1 draw with Nuremberg last weekend.
That run sees them hold an identical record to champions Bayern Munich, and they will bid to maintain their unbeaten run when they take on Freiburg at Signal Iduna Park on Saturday.
But Klopp, who has won two Bundesliga titles and a DFB-Pokal crown in his time at Dortmund, feels that they still have further strides to make.
"We must run a lot, invest a lot, play a lot of football and quite simply take the next step in our development," he said.
"The funny thing about recent times is that the mood has not been so good. In Naples (against Napoli in the UEFA Champions League) I pushed the mood a little too far - and then we still lost - but that was our only loss up to now."
Dortmund are hampered by a number of injuries ahead of the Freiburg clash, with midfielders Sebastian Kehl and Ilkay Gundogan and defender Lukasz Piszczek all unavailable.
In spite of those absences, though, Klopp is happy with his squad and feels that they have the quality to take the next step.
"I would like to see us develop in a playful way," he added.
"To do this it would be helpful if we had all the guys at our disposal."
