The 31-year-old has featured on six occasions for the Catalan giants during the 2023-24 campaign, and he scored his first goal of the season in the 2-2 draw with Granada before the international break.
Roberto entered the field in the 61st minute and was able to finish the contest, but he has now suffered a muscular injury during a training session.
Barcelona have not provided a timeframe in terms of a potential recovery for the Spaniard, but journalist Toni Juanmarti has claimed that he will be out for between two and three weeks.
As a result, Roberto is set to miss the upcoming clashes with Athletic Bilbao, Shakhtar Donetsk and Real Madrid, but he could potentially be back against Real Sociedad on November 4.
"First-team player Sergi Roberto has a soleus muscle injury in his right leg and will be unable to play until the problem goes away," read a statement from the Catalan side.
There remains uncertainty surrounding Roberto's future at Camp Nou, with the player said to be eyeing a move to the MLS when his contract expires next June.
Barcelona allegedly received a double injury boost on Wednesday, though, with Lamine Yamal and Alejandro Balde both said to have trained with the club.
Yamal withdrew from the Spain squad due to an injury that he picked up during the clash with Granada, while Balde suffered an adductor issue while representing La Roja again Scotland.
According to Juanmarti, the pair were both in training on Wednesday, fuelling suggestions that they could be available for the contest with Athletic this weekend.
However, Robert Lewandowski, Jules Kounde, Frenkie de Jong, Raphinha and Pedri remain unavailable for selection.
Barcelona are working to recover injured players for El Clasico at the end of the month, and it is understood that Lewandowski, Raphinha and Pedri could return for that contest.
Xavi's side remain unbeaten in all competitions this season, but they are third in the La Liga table, three points behind the leaders Real Madrid on the same number of matches (nine).