The 25-year-old completed a move to Paris Saint-Germain last month after the French side paid his €222 million release clause, shattering the record for the most expensive signing in history.
Bartomeu was clearly left dismayed by the antics of Neymar and his father and agent Neymar Santos Sr., who was a driving force behind the move to Paris.
"We made the mistake of trusting Neymar and his father too much," Bartomeu said.
When an Instagram account posted Bartomeu's quote, Neymar couldn't help but respond in the comments section, saying: "This president is a joke".
Barcelona signed Ousmane Dembele to help replace the Brazilian, who is off to a fast start in his time at PSG.
The forward has three goals and three assists in three league matches for the French giants so far – all of them wins.