But services would be provided at more specialist regional centres and in the community, she added.
She told BBC One's Politics Show that local hospitals were changing because modern medicine was changing.
Campaigners say a rising number of protests over the NHS could rival the 1990s rebellion against the poll tax.
Local decisions
Ms Hewitt said district general hospitals would continue to change but would not disappear and that more medical services would operate in a community setting.
"With medicine becoming increasingly complex and specialised there are some cases for which you are much safer in a specialist centre," she said.
"You will still need local hospitals but they won't be the same as they were 10, 20, 30 years ago.
"We will have a different range of hospitals. We're not sitting in London trying to work out what the right solution is in different places.
"It means that these decisions get made locally."
She said there would "almost certainly" be a smaller number of hospitals offering a full range of services.
"What I think will happen in the next few years is we will have a limited number of regional specialist centres that will treat people who need that particular type of treatment. But that is an improvement, not a cut," she said.
Turned out
Demonstrators against changes to the NHS were due to form a human chain around a West Sussex hospital on Sunday, and several rallies took place on Saturday.
In recent weeks demonstrators have also turned out in other parts of the country.
The protests have attracted both health professionals and members of the public affected by potential changes.
NHS trusts are looking at shifting care away from hospitals into community settings and placing greater emphasis on the private sector.
In all, 60 sites are said to be under threat.
The Department of Health said the government's white paper on the future of hospital services was "based on what the public told us they wanted from community and primary health services".
source: www.bbc.co.uk
