Now with Inter Miami, Messi left the club in the summer of 2021 after his contract expired.
Current president Joan Laporta has long stated his predecessor was responsible for Messi leaving the club.
But now Bartomeu has given his view of the situation.
"If they had done what was needed, it would have been entirely possible to extend Leo Messi's contract and sign players," Bartomeu told Goal.
He instead believes that the responsibility lies in how the club's finances were handled after his time in power.
“It wasn't the inheritance that was the problem, it was Financial Fair Play. The new board increased the reported losses to 555 million euros,” he said.
"When La Liga re-examined the figures, it was concluded that the losses were actually lower, as 283 million euros were provisions. Despite this, Barcelona chose to stand by its line. La Liga then applied the regulations, which led to a financial penalty from which the club has still not recovered."
He also believes that Messi was not treated fairly in connection with the departure.
"Messi was underpaid in terms of what he contributed, both on and off the pitch. He wanted to be part of the team's renewal with the young players we have today, but he had to leave and that couldn't be changed," added Bartomeu.