Malaga defender Luis Hernandez said it was "absurd" to allow Barcelona's opening goal to stand as his side lost 2-0 at the Camp Nou on Saturday.
Barca benefited from a touch of good fortune with their opening goal inside two minutes.
Lucas Digne weaved into the left side of the Malaga penalty area, but his touch from a rebound off a defender took the ball over the byline and out of play before he crossed into the six-yard box where Deulofeu flicked the ball in for his first Barcelona goal.
Despite the angry protest of the Malaga players, referee Pablo Gonzalez Fuertes was not moved and ran back towards the centre-circle.
Hernandez, however, was sure of the injustice, saying: "I can understand that they say it didn't go out, but it's absurd, the ball was half a metre out over the line. Once again, a decision is made that we suffer from."
Malaga have just one point from their opening nine games, and Hernandez said a number of recent decisions are at least partly to blame for the misfortune.
"I always say that the referee's job is a difficult one, but we conceded a goal against Eibar that was offside and another one against Valencia last Sunday," he said.
"We are not going to blame the referees for our place in the league, but it's hurting us a lot."
For his part, Deulofeu felt he was well within his rights to put the ball in the net.
I didn't see a problem. I still have not seen a replay of the incident, but for me it was legal," he told BeIN Sports. "I believe this, hence why I played on."