The prolific attacker was forced to pull out of the Argentina squad for the upcoming 2018 World Cup qualifier against Venezuela, having previously guided them to a 1-0 win over Uruguay after reversing his decision to retire from international football.
Messi underwent a series of tests on Monday to determine the extent of the knock.
Barcelona have now confirmed the forward's adductor issue and have made it clear Messi will have to lighten his training load ahead of this weekend's match at Camp Nou.
