Messi struggled to influence the match in Rio de Janeiro on Sunday night as Germany were crowned champions with an extra-time victory.
While the 27-year-old was controversially named player of the tournament, Kempes believes that Messi did not live up to his own lofty standards in Brazil.
"Argentina needed Messi like a fish needs water but he needed to be more involved. We lacked his footballing brain," he is quoted as saying by Goal.com.
"I think that Messi wasn't up to standard during the World Cup. He may have scored four goals in the first few games but I don't believe he showed he was the best player in the world by the end of the tournament."
Messi has scored 42 goals in 93 appearances for the Argentine national team.