United's England midfielder was given a taste of the abuse he will have to endure over the coming months when he was jeered every time he touched the ball during the Charity Shield defeat against Arsenal.
Supporters are using Beckham's sending off during England's game against Argentina in the World Cup as an excuse for the campaign of vilification, and the Arsenal manager, Arsene Wenger, fears that the abuse could go on for months yet. United's first away game of the new Premiership season is at West Ham on 22 August, where supporters have been planning a hostile reception for Beckham involving the distribution of hundreds of red cards among the crowd.
Keane says the abuse is totally unjustified, but has himself learned to live with being targeted by the fans of opposing teams and he firmly believes that Beckham can do the same.
"Becks is old enough and mature enough to deal with this," he said. "He's paid to play football and while it's easy for us to say, basically he's just got to try and ignore it and let his feet do the talking.
"He's a good lad. The criticism he's getting is obviously undeserved, but with football fans there are a few idiots about. We are professionals and are paid to play football - that's what it is about at the end of the day, not listening to some idiots shouting their mouths off."
Keane suggested that Beckham should look at the abuse in a positive way and use it to spur him on.
"He should take it as a compliment because I'm sure the fans who are giving him stick would all love him to play in their team," he pointed out. "He's got to realise that and get on with the business of playing well and winning matches for Manchester United."