The Reds succumbed to a 3-0 first-leg defeat after Luis Suarez scored the crucial break-through goal and Lionel Messi netted twice to put Barca in the driving seat.
Keita, who started alongside Fabinho and James Milner in central midfield, showed glimpses of his talent in the opening exchanges but appeared to struggle after being involved in a challenge with Ivan Rakitic.
The Guinean clutched his groin as he was forced off the field due to injury, with skipper Jordan Henderson replacing him in the 24th minute.
Speaking after the game, Klopp was unsure whether Keita would be involved again this campaign, insisting: “We have to see. It didn't look good in the moment after.
“He will have a scan tomorrow I'm sure and then we will see if there is a decision to be made. I think it was his groin.”
Keita is now a major doubt for Liverpool's trip to Newcastle on Saturday evening as they look to return to the top of Premier League table.
Should initial fears over the midfielder be realised, he could also be out for the Reds' final two games of the season: the second-leg vs Barcelona on Tuesday and the visit of Wolves on the last day of the Premier League season.
It is another huge blow for Liverpool and Keita, who has endured a stop-start debut season at Anfield since his arrival last summer.
Keita has impressed in recent weeks after a lacklustre start to his Reds career, scoring three goals and recording one assist in 33 games in all competitions this season.
Liverpool have it all to do in the second-leg against Ernesto Valverde's side and Keita's involvement would be a huge boost should he be fit enough to feature.