In the lead up to their Champions League opener with Ferencvaros, Koeman admitted he was expecting more from Messi so far this season.
"Currently, his performance could be better," said the Dutchman.
El Chiringuito's Jose Alvarez has reported the words of Koeman have not gone down well with Messi's minders. Those behind the Argentine were left unimpressed by the public criticism.
However, Messi himself isn't overreacting to Koeman's comments, accepting he needs to step up his game after Barca's disappointing start to the campaign.