The former Manchester United captain has indicated that he will deal with claims made by Sir Alex Ferguson but admits that he has mellowed with age
Since assuming his new role with the Republic of Ireland, Keane has repeatedly dismissed queries about his relationship with Ferguson, who criticised the 42-year-old in his new autobiography. However, the Cork native suggested that he would "lock horns" with Ferguson at a later stage.
"There will be a day for me to go into stuff like that," Keane told reporters. "I've no problem with people having opinions but when people tell lies about me, ultimately you have to come out and defend yourself and I will do, but it's not today."
Keane admitted that he had mellowed "a little bit" but insisted that "you have to be ready to lock horns" with opponents and critics.
"I hope we all mellow. I think I have a little bit, of course," he added. "As you get older, hopefully you get a bit wiser but also you have to be ready to lock horns with people."
The former Ireland captain also stressed the importance of confidence and self-belief when playing against "big teams" and said that he did not want the players to be "fearful" of the opposition.
He said: "I never ever remember once in my career ever sitting in a dressing-room with Ireland, and we played some big teams; Italy, Germany, the Dutch, the Portuguese. I don't ever remember looking at players and having any sort of fear and going, 'I'd take a 2-0 defeat here today'. No, no. Let's go for it.
"I don't want to be looking around the dressing-room at players who are fearful in terms of going out and doing their best.
"Yeah, you can be fearful of losing a game but having that self-belief that whoever is going to beat the Irish team are going to have to play well."
Meanwhile, Republic of Ireland manager Martin O'Neill must contend with further squad withdrawals as Joey O'Brien pulled out of the Ireland squad with a hamstring injury.
The West Ham defender joins Andy Reid on the injury list as the Boys in Green finalise their preparations ahead of the clash against Poland on Tuesday.