Odell Beckham says he had a golden opportunity to retaliate against Marlon Humphrey after Sunday's choking incident ... but chose not to fight back because "it's not MMA."
The Cleveland Browns WR says he was fined by the NFL for the incident -- even though he claims he was not the aggressor and was only defending himself.
But Beckham says things could have been WAYYYY worse ... if he wasn't such a mature and restrained person.
"There was an opportunity for me to really take things way further," Beckham said.