Rafael's eight-year spell at United came to an end last week when he signed for Lyon for £2.1million.
The Brazilian was a regular starter during Sir Alex Ferguson's final year in charge at Old Trafford, but fell out of favour under David Moyes and started just six Premier League games under Van Gaal last season.
While Rafael said he did not know if the fact that he is Brazilian had an effect on his exit - Van Gaal clashed with Giovanni and Rivaldo when at Barcelona - the right-back was left with the impression that the United boss was certainly not a fan of his
"I know this history that he doesn't like Brazilians, but I can't say: 'Oh, he doesn't like Brazilians.'," Rafael told Globo Esporte.
"I know that he didn't like me, but if that's because I'm Brazilian, I don't know.
"The truth is that after Van Gaal arrived, I played little
And a player always wants to play.
"Here (at Lyon) I have more playing opportunities."
Rafael's relationship was clearly stronger with Ferguson, who rang the Brazilian after his move to Lyon went through.
The 25-year-old claims Ferguson's retirement in 2013 was "fatal" to his chances of forging a longer career at Old Trafford.
"I did the complete season, when he [Ferguson] left," he added
"In 2012-13 I played almost every game, it was my best season at United, we were even champions.
"And that's when they changed the manager
That change was fatal for me
I was going well, then Ferguson left."
Source : PA
Source: PA