Cantona is an extremely violent person who just loves fighting people. Here's Wikipedia's take on the incident:
On 25 January 1995 he was involved in an incident that attracted headlines and controversy worldwide. In an away match against Crystal Palace, Cantona was sent off by the referee for kicking Palace defender Richard Shaw after Shaw had frustrated Cantona throughout the game by closely marking him. As he was walking towards the tunnel, Cantona launched a 'kung-fu' style kick into the crowd, directed at Crystal Palace fan Matthew Simmons, a fan who had run down 11 rows of stairs to confront and shout abuse at Cantona. Simmons was alleged to have used the words "Fuck off back to France, you French bastard". Cantona followed the kick with a series of punches. A lengthy ban from the game was regarded as inevitable, with some critics calling for Cantona to be deported and never allowed to play football in England again, while others called for him to be banned from football for life.
As well as disciplinary action from his club and The FA, Cantona was also faced with a criminal charge of assault, which he admitted to on 23 March, resulting in a two-week prison sentence, although he was freed on bail pending an appeal. This was overturned in the appeal court a week later and instead he was sentenced to 120 hours of community service, which was spent coaching children at Manchester United's training ground. At a press conference called later, Cantona said, in a slow and deliberate manner:
"When the seagulls follow the trawler, it's because they think sardines will be thrown into the sea. Thank you very much.”
—Cantona’s brief, and much publicised, statement
Cantona then got up from his seat and abruptly left, leaving behind him a packed media room surprised and baffled – some roared with laughter – with those in the room trying to decipher his cryptic words. In accordance with The FA's wishes, Manchester United's initial action was to fine Cantona £20,000 for the assault and to confirm that he would not play for the first team for the rest of the season, although Manchester United were still in the hunt for a second double. He was also stripped of the captaincy of the French national football team by national coach Aimé Jacquet. The FA then increased the ban to eight months (up to and including 30 September 1995) and fined him a further £10,000. The FA Chief Executive Graham Kelly described his attack as "a stain on our game" that brought shame on football. FIFA then confirmed the suspension as worldwide, meaning that Cantona could not escape the ban by being transferred or loaned to a foreign club. Cantona never played for the French national team again. His club eventually lost the Premier League title to Blackburn Rovers.