Stark failed to award Barca a penalty when it appeared Thierry Henry was fouled in the area by Chelsea defender Jose Bosingwa.
“There are no excuses for that referee,” he told Sky Sport.
“I think there was a clear penalty on Henry. He was always stopping play even though we had the advantage to continue out attacks.
“Chelsea were not interested to play, they were committing little fouls to stop our movement.
“We still have the second leg but they are a difficult team on their own ground. But we can win anywhere in the world and we will go for a win.”
