The striker, 32, has already signed a pre-contract agreement with the Bluebirds, but the Spaniard was recently quoted as suggesting that the move may not go through.
However, Suarez is confident that Guerra - whose contract expires this summer - will end up at the South Wales club.
He told La Cadena Ser: "Javi Guerra will for sure go to Cardiff this summer and I'm happy for him. There is no possibility that he will continue with us next season."
Guerra has struck 13 times in 32 Liga appearances for Valladolid this season.