كتب : Hatem Maher
The Swedish international converted the penalty six minutes before the break after Xavi was apparently impeded by Raul Baena.
Television replays suggested there was a minimal contact between both players in the box.
Barcelona, who had to do without Ballon d'Or winner Lionel Messi due to injury, had earlier missed a goalscoring opportunity when winger Pedro fired wide with the goal at his mercy.
Ibrahimovic took his tally to 11 goals in 15 league games this season to become joint top scorer with Valencia's David Villa.
The Catalan giants, who eye a second consecutive league triumph, are on top with 39 points, five clear of second-placed Real Madrid who secured a 3-2 victory over Valencia later in the day.
A brace from Argentinean forward Gonzalo Higuain helped Real to a precious win at the Mestalla.
Ibrahimovic goal