Messi wanted to finish his career with the Catalan giants, but the club's financial problems meant that they could not hand the Argentina international a new contract, and he instead made the move to Paris Saint-Germain.
Bartomeu, who was replaced as president on a permanent basis by Laporta, has said that it was "a bad decision" from the current board to allow the experienced attacker to move on.
"They let Messi leave and that seems like a bad decision to me," Bartomeu told reporters. "Playing without Messi shows that a lot of things have to change. As president, I didn't want Messi to leave and I did everything I could to prevent it from happening."
The 34-year-old scored 672 goals and registered 301 assists in 778 appearances for Barcelona before his contract expired at the end of June.
Messi has since found the back of the net on one occasion in five outings for PSG, with the strike coming against Manchester City in the Champions League. body check tags ::