Ernesto Valverde had to replace Dembele just six minutes into the 2-0 defeat to Celta Vigo in LaLiga on Saturday and the France international was not included in the travelling party for Tuesday’s game at Anfield.
Barca announced that tests carried out Sunday confirmed a hamstring problem, but did not supply a timeframe for the 21-year-old’s return to the pitch.
Dembele started the 3-0 first-leg triumph on Wednesday among the substitutes as Philippe Coutinho was preferred in the front three.
The former Borussia Dortmund attacker has suffered a series of injuries since arriving at Camp Nou in August 2017, with ankle and thigh issues causing him to miss time this year alone.
Speaking after the defeat to Celta, Valverde said:
“It is a major setback for us ahead the next game at Anfield and for the rest of the season. It happened in the first play of the game and we noticed straight away.
“He was attacking with a long ball and when he tried to sprint to win the ball, we noticed that something was not right.
“When a player has some muscular tear his level on the pitch slowly start to decrease, but as it was so clear, we decided to take him off the pitch to avoid further damage.
“Apparently he has a muscle problem, but we must wait and do some tests.”