The Spanish international left the field in tears on Sunday after twisting his knee during Spain's 3-1 win over Georgia. An MRI scan confirmed he had injured his right knee in addition to tearing his ACL.
"The Andalusian midfielder is a favourite amongst the fans. Gavi's spirit and determination on the field are what defines him as a player and he gives absolutely everything in a Barca shirt. For that reason his injury is a big blow for all Barca fans and so here is a chance to send him a message of support," Barcelona said in an official statement.
During last year's World Cup in Qatar, he became the youngest scorer at the tournament since Pele in 1958 after helping Spain to thrash Costa Rica 7-0.
"It is a very difficult moment for Gavi, Barcelona, the national team and for me, it seems as if we have lost the game," Spain manager Luis de la Fuente told a press conference on Sunday.
"This is the ugly part of football. I am very sorry. This is the most bitter victory I have ever experienced in my life."