When asked about the impact on patient care, he said: "Of course there are always up-front costs. And yes there is always a risk of disruption."
Streeting said former health secretaries had "not been prepared to take on those sorts of challenges" and argued NHS England "was set up to shield politicians like me from responsibility".
He said: "I've seen waste, inefficiency and duplication. So of course we should go after that."
When asked for a second time if patient care would be disrupted by the government's reorganisation of the NHS, Streeting promised to deliver improvements and said waiting lists for treatment had already been falling.