The Manchester City man was reportedly involved in a heated exchange with a member of the press who asked to speak with him after Laurent Blanc's side were beaten 2-0 by defending champions Spain in the quarter-final in Donetsk.
Le Graet condemned Nasri's actions and warned the player he must assert more self-control in future.
He told French radio station RMC: "I will ask the journalist to meet with me, but this is intolerable.
"I understand that there are negative reactions. Samir is on the edge, he wants to do well, but he cannot control his impulses."
Les Bleus' elimination will no doubt increase speculation over the future of coach Blanc, who has overseen an upturn in fortunes since replacing Raymond Domenech following the farcical World Cup campaign two years ago.
Blanc, who has been linked with the managerial vacancy at Tottenham, had wanted his France contract extended before the European Championship.
Le Graet has no news yet on whether Blanc will remain in the role, but expects to hold talks soon with the 46-year-old former Manchester United defender.
"I saw Laurent last night [Saturday]," the FFF chief added.
"We promised not to talk about this during the Euros.
"We will meet soon to discuss the future. We must give it a week to take stock at leisure. We will meet within eight days and we will have a position, I imagine, in common.
"As a man, Laurent is completely respectable and pleasant. We must talk about football, his desire and his career. We must see how he sees things and how I see them."
Assessing France's overall Euro 2012 campaign, Le Graet took heart from the Group D victory over Ukraine - Les Bleus' first in the finals of a major tournament in six years - but accepted they had some way to go yet before they would be considered a force again.
"This has been an acceptable European Championship," he said.
"Qualifying was anguish, but we achieved it despite the performance against Sweden [2-0 defeat] - a pitiful game for the national team. We did not help yesterday [Saturday]. This is an acceptable Euro, but no more.
"The Spanish were better, with a collective level higher than ours. Nevertheless, there was nothing to be ashamed of. Spain did not create many opportunities, but we did not perform very well in attack.
"The opponents were too strong for a France team that has progressed, but is not yet at their level.
"We have made progress. We are 16th in the FIFA rankings and we ended up in the last eight of the European Championship. That was our goal, and it was realised.
"But to imagine that our team is the best... it's not a good analysis. Our current staff cannot be champions of Europe. I wish to go further but we must be realistic.
"There are gaps. There have been real developments but the road is still long to become a team that others fear."
He added: "We had not won a game in international competition since 2006. I try to find positive things - that is my role. We are in a period of transition. Obviously, I would like it to go faster."