The Friends of Bridgnorth Library say it vital the facilities continue providing multi-use hubs and meeting places for people of all ages.
Shropshire Council plans to hand over responsibility for libraries across the county in a bid to save £1.1 million from its budget.
The proposals include looking at new ways of running the county's large libraries, including Bridgnorth.
Neil Hancock, a member of the Friends group, said: "We have concerns following the recent, much-reported approval of plans, which will inevitably result in closure or privatisation of libraries across the county.
"This decision can only be regarded as a misconceived and retrograde step.
"The quoted saving of £1.1 million would have a negligible impact on the council's £100 million budget reduction target, but a huge detrimental effect on the communities our libraries serve.
"Our libraries are a public asset, not a liability to be disposed of or privatised via a commissioning policy. Driven by qualified management and staff they are multi-use hubs and meeting places offering the key to learning for all ages."
"They provide a cost-effective, value for money service for both Shropshire Council and visitors alike."
The Friends of Bridgnorth Library has urged Shropshire Council's cabinet to "urgently re-think" the proposal and to openly consult with the public to ensure the long-term future and provision of the service.
Mr Hancock said: "We would also urge all those who use Shropshire library services to make their views on this matter known to their Shropshire councillor and their member of parliament."
Councillor Steve Charmley, cabinet member for business and culture, has previously said that closing libraries was the "last thing" Shropshire Council wanted to do.
He said: "It's not the way we want to do it. Closing them would be the easy option.
"We've pulled the libraries into two pots, we've got the bigger libraries in market towns who we are looking to work with community groups and other organisations, and the smaller libraries.
"A good example of one of our bigger libraries is Oswestry library which has become a hub and it does demonstrate that libraries aren't just about books any more."
"We're moving more of our customer service points into the libraries, which is driving increased use."