Barcelona says an MRI revealed the World Cup champion suffered a small muscle tear in his left leg.
Barcelona must overturn a 2-1 deficit to Arsenal in the return leg of their last-16 series, which will be played on March 8 at the Camp Nou Stadium.
Xavi is expected to miss the Spanish champion's match at Mallorca on Saturday and another league game against Valencia next week. Barcelona plays Zaragoza on March 5.
Barcelona holds a five-point lead over Real Madrid in the league table.