The Argentina star will leave the Catalan club after 21 years following negotiations over a new deal fell apart on Thursday.
"Despite FC Barcelona and Lionel Messi having reached an agreement and the clear intention of both parties to sign a new contract today, this cannot happen because of financial and structural obstacles (Spanish Liga regulations).
"As a result of this situation, Messi shall not be staying on at FC Barcelona. Both parties deeply regret that the wishes of the player and the club will ultimately not be fulfilled.
"FC Barcelona wholeheartedly expresses its gratitude to the player for his contribution to the aggrandisement of the club and wishes him all the very best for the future in his personal and professional life."
The 34-year-old was set to accept a deal that would see his weekly wage reduced by 50 per cent.
But the club's financial situation made it impossible for them to register him for the new season without drastically reducing their wage bill.