Sevilla president Jose Maria del Nido insists the club would only swap Daniel Alves for Lionel Messi if Barcelona paid an additional 30million euros.
Alves was strongly linked with a move to Chelsea last season, while Real Madrid are also thought to be keen on the attacking full-back.
A number of clubs are understood to be ready to test Sevilla's resolve again this summer and Barcelona have been rumoured to be favourites to land the Brazilian.
However, Del Nido has labelled Alves the 'best player in Spain' and is adamant he would only agree to a hypothetical swap deal for Barcelona star Messi if the Catalan club paid an additional 30m euros (£22m).
When asked if he would swap Alves, Del Nido told reporters: "For absolutely nobody. For Messi and for £30million euros. Alves is the best player in the league now.
"We have to be careful and be open. But I guarantee you that if Sevilla do not want to sell, then we will not sell."