The Brazilian international agreed to link up with the Spanish champions later this summer from Santos for £50m.
Discussing the 21-year-old's arrival, Cruyff has questioned if there will be enough room at Camp Nou for both him and Messi.
"With Neymar on board, I would have planned for the possibility of selling Messi. Some would agree with that, others not," he said.
Messi has scored 313 goals in 379 appearances for the Catalan club.