"It is very regrettable but it's a problem between Samir and the press. It is very, very bad for his image but when this is done when he's with France it's also bad for the team's image," Blanc told French TV station TF1 on Sunday.
"From what I gathered, he lacked respect towards the journalist who at some point also lacked respect towards him."
Midfielder Nasri had already been involved in a row with the media at the tournament when he muttered "shut up" after scoring the equaliser in France's 1-1 draw against England in their opening game.
"I had told him what I thought about this [after the first incident] but apparently he did not get the message," added Blanc.
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