Barcelona coach Quique Setien has revealed he has apologised to the players and everyone at the club for the exuberant behaviour of his assistant coach Eder Sarabia on the touchline during last week's 2-0 defeat by Real Madrid.

Sarabia was a little-known figure until Spanish television show Vamos broadcast images of his reactions from the dugout during Sunday's 'Clasico', using a lip-reader to reveal some of the disparaging comments he made about his side's players.

The assistant coach was seen criticising Antoine Griezmann for failing to convert one of his chances and repeatedly used foul language in response to Barca's performance during the game.

Spanish media reports said the footage had not gone down well among Barca's players and Setien said he had told his assistant that he needed to consider his touchline antics.

"We apologised to everyone, we cannot behave like that," Setien told newspaper El Periodico on Thursday.

"We don't like to see things like this, we have committed an error and we should try to avoid something like this happening again.

"This situation has affected me a lot, because I am concerned about the image of the club. We need to take care of that image, because we can be criticised for substitutions, tactics, etc, but not for our behaviour."

Sarabia, 39, began working alongside Setien in 2015, following him to Real Betis two years later and to Barca in January this year when the 61-year-old became coach of the Catalan club after Ernesto Valverde was sacked.

The manager said Sarabia's animated personality was often a strength but stressed that he needs to work on the image he portrays of himself during matches.

"It's true that you have to understand how people are at certain moments, we are not all the same. Eder has a great temperament, and in many situations it helps us phenomenally well. But he has to learn to control himself," Setien said.

"He's trying to do that, he's trying to improve in this area because we have had situations like this before. They are becoming rarer, but it's something that we don't like to see."

The coach also said he was disappointed with how the footage came out and how it had been interpreted.

"It's a bit of an embarrassment that this has become a news story and has provoked such a huge reaction," he added.

"It's shameful that the broadcaster used a camera to follow you the whole time on the touchline. It's something that should be eradicated. You should not have to cover your mouth the whole time."