Speaking at the Liberal Democrat conference in Liverpool, Cable promised that despite the planned privatisation of Royal Mail, the Post Office "is not for sale" and "there will be no repeat of the previous closure programmes".
Under the previous government, 6,400 branches were closed. However, Cable's pledge will be written into the Postal Services Bill which will be introduced later this autumn.
Mark Bamforth of Lytham St Anne's Post Office in Lancashire welcomed the news and said it could be the start of a resurgence in the network. "We were marked for closure several years back but survived," he said. "Business has improved and there seems to be more stability in the network."
Derek Gillpin of Frizington Post Office in Cumbria warned that the network still needed to offer customers more services to prevent future closures. "If we could provide other services we would have a better chance at survival," he said.