"I told the president and, well, the president always said that at the end of the season I could decide if I wanted to go or if I wanted to stay, and in the end, he did not keep his word," Messi told Goal.
Messi added: "Throughout the year I had been telling the president that I wanted to leave, that the time had come to seek new goals and new directions in my career. He told me all the time, 'We'll talk, not now, this and that,' but nothing. The president did not give me a clue (as to) what he was really saying."
The 33-year-old tried to engineer a move away from Barcelona - where he's spent his entire professional career - but ultimately reversed course when the club denied his attempt to terminate his contract.
Bartomeu reportedly told Messi's father during a meeting Wednesday that he could leave only if a team paid his €700-million release clause in full, and that the clause allowing the player to terminate his contract expired in June.
Messi's camp countered by saying the deadline to activate the termination clause should've been extended due to the delay to the season caused by the coronavirus pandemic.
"I thought and was sure that I was free to leave," Messi said.
"Now they cling to the fact that I did not say it before June 10, when it turns out that on June 10 we were competing for La Liga in the middle of this awful coronavirus, and this disease altered all the season," Messi added. "And this is the reason why I am going to continue in the club. Now I am going to continue in the club because the president told me that the only way to leave was to pay the €700 million."
Messi said he made up his mind well before the 8-2 defeat to Bayern Munich in the Champions League quarterfinals on Aug. 14. He officially submitted his notice to Barcelona on Aug. 25.
"I believed that the club needed more young players, new players, and I thought my time in Barcelona was over," he said. "I felt very sorry because I always said that I wanted to finish my career here.
"It was a difficult year. I suffered a lot in training, in games, and in the dressing room. Everything became very difficult for me, and there came a time when I considered looking for new ambitions."