Messi said his priority was to return as soon as possible so he could contribute to the Spanish champions\' quest for silverware.
Barcelona: Lionel Messi will be working "full time" to shake off the hamstring injury sustained on Sunday that will sideline him for six to eight weeks, Barcelona's Argentine World Player of the Year said on Tuesday.
In his first public remarks since he was forced off early in Barca's 4-1 La Liga win at Real Betis, Messi said his priority was to return as soon as possible so he could contribute to the Spanish champions' quest for silverware.
"As many of you know, over the next few weeks I will be working full time on the recovery from this latest injury," Messi said on his Facebook page.
"For me it is a pity not to be able to play with my team right now," added the 26-year-old.
"Now the most important thing is to recover well so I can help my team mates and reward all the support you've given to me in the best way I know how to do, playing football."
Messi was substituted in the 19th minute in Seville after pulling up following a sprint for possession and a tangle with his markers. It was his third thigh injury of the campaign and followed a similar muscle problem towards the end of last season.
His absence is perhaps not as serious as it might first appear as he will likely return before Barca face title rivals Atletico Madrid in January and they have already qualified for the last 16 of the Champions League.
In Brazil forward Neymar, signed from Santos in the close season, Barca have a player with a similar ability to turn a game and the 21-year-old will be expected to justify his 57 million-euro price tag while Messi is out.
The Argentine will miss Barca's final two matches in the group stage of Europe's elite club competition, against Ajax Amsterdam and Celtic.
He will also be unavailable for La Liga games against Granada, Athletic Bilbao, Villarreal and Getafe and the two-legged King's Cup tie against Cartagena but should return in time for the La Liga clash at Atletico the weekend of January 11-12.
Barca top the standings by three points from Atletico and six from arch-rivals Real Madrid in third.