Mike Farrar, chief executive of the NHS Confederation, told BBC Radio 4's Today programme: "The Secretary of State is right to say we should aspire to be world-class. We all do that.
"The fact is that you shouldn't infer that we are not trying. The key thing is how do we make sure that everybody can get to be world-class in every bit of their organisation and hospital. That's the challenge for us."
Mr Farrar said a key factor in driving improvement was the publication of data on performance, which he said can spur better outcomes across the service.
"The NHS has failed, I think, in comparing performance in a transparent way," he said. "Where we've seen the NHS compare its results, that's been a great catalyst for staff to want to improve.
"But you do then have to put the resource in to train and educate people how to be the best in the world. It's not just about aspiration, you've got to give them the resources and the wherewithal to be the best in the world."
More top news
The rain band will soon be clearing eastwards, but more showers will be affecting parts of the UK this afternoon.
David Cameron will stand down as Conservative leader ahead of the general election expected in 2020, Iain Duncan Smith said.
Delegates at the SNP spring conference have backed a move to allow all-female shortlists in the Scottish Parliament election next year.