Messi was substituted in the 73rd minute after asking to be taken off while holding the back of his thigh. He then disappeared down the players' tunnel.
"He was exhausted; the pitch was heavy. When there is concern, you don't want to take any risks," Miami coach Guillermo Hoyos said, according to Argentine newspaper Diario, adding that Messi will undergo tests.
Despite being forced to leave, Messi's Miami team won 6–4 against Philadelphia.
Argentina's national team coach Lionel Scaloni has so far announced a 35-man squad for the World Cup. The final 26 names who will defend the World Cup title will be presented next week.
Messi, 38, will make his sixth World Cup in North America - unless last night's injury puts an end to it.
Argentina will play their first World Cup match against Algeria on June 17.
