Guardiola was offered a six-year deal in the summer by incoming president Sandro Rosell, but preferred to sign up for just two more seasons.
The Spanish press recently claimed the Barca boss was Sir Alex Ferguson's choice to succeed him at Old Trafford, but Zubizarreta believes Guardiola's ties with the Catalan run too deep for him to think about leaving just three years into his highly successful tenure.
"If Ferguson is thinking that way, he has excellent taste," the former Barca and Spain goalkeeper told Ona FM yesterday.
"But everybody knows the ties Guardiola has with Barca, which go far beyond the contract he has."
And Zubizarreta insists he is working on a long-term project with his former club and international team-mate.
"There is nothing we are keeping (from people) and nothing holding us back - we are working on a long-term project," he said.