The Rams endured a frustrating season in the Championship last term, managing just ninth place in the league - 13 points off the playoffs - despite losing just two of their games following Rowett's appointment in mid-March.
Rowett has been frustrated in his attempts to get transfer business done this summer, meanwhile, and has thus far signed only defenders Curtis Davies and Andre Wisdom, as well as midfielder Tom Huddlestone.
"I understand at this stage that some people have the opinion that we are not doing anything or we are not trying to do anything or we think we are alright," Rowett told the Derby Telegraph. "We don't, we are and we are working incredibly hard.
"Behind the scenes in the past two months we have literally been trying to do deals every single day. Of course, they are never easy to do unless you hugely over pay.
"You can get any deal done if you pay stupid money but the reality is we don't want to do that and I don't think it is the right thing for this club to be doing that, at this moment."