Dortmund lost in the final of the Champions League at the weekend and are set to lose Mario Gotze and Robert Lewandowski this summer.
“I have read that we have a difficult season ahead of us, which doesn’t make sense because we have such a good base and such good quality,” he told Bild.
“Naturally, there will be a couple of changes and one or two players will leave. But breakup is the wrong word, there are simply a few changes which we think we can use to our advantage. I’m quite positive.
“I can promise that everything will work out in the end. We are building a new team, a new pressing machine.”