The World Cup winner was released from the remaining year of his contract last week and immediatly singled out the Dutchman as the reason he left Camp Nou.
However, talking in a press conference on Wednesday, the former Ajax coach blamed the player for not being committed to the club.
"He lacked commitment to the club, he was only interested in making more money and playing less," blasted van Gaal.
"He was chosen as the best player in 1999, but he has not handled himself well since then and has not behaved like a footballer should.
"He had illusions about Barca and was requesting to take holidays when important Champions League games were approaching. He then hides back home in Brazil.
"He plays for Brazil like we needed him to at Barcelona, and he has proved this in the World Cup finals, showing he reserved himself for Japan."
Van Gaal also stated that he tried to get rid off him during his previous tenure as Barca chief.
"Three years ago I tried to sell him, but Jose Luis Nunez stopped the transfer," he confirmed.
The Dutch coach then admitted that he would not be bothered if he made the controversial switch to rivals Real Madrid.
"I have no worries if he wants to go to Real Madrid," he added.
The destination of Rivaldo is still a mystery and a host of clubs from Spain, Italy and England have all been linked.
One club to confirm their interest, and who are reported to be leading the chase, are Milan.
Their vice-president Adriano Galliani has stated that the club are looking into a deal to take him to Giuseppe Meazza.
"I can confirm that Milan are in negotiations with Rivaldo in the hope that an agreement can be reached," Galliani told the Milan website.
"I hope that his wage demands are compatible with our club structure.
"We hope that the player's requests can be met in order to successfully conclude the deal."