Blatter all but confirmed at FIFA's annual Congress on Wednesday that he would run for a fifth term next year despite criticism that the game and organisation have been tarnished by accusations of corruption during his long reign.
"I do not support him," Platini, head of European soccer's governing body, was quoted as saying by French sports newspaper L'Equipe on Thursday. "I have known him for a long time and I like him well but I am not in favour of him doing another term."
The Frenchman, a former world class player, is seen as a likely opponent to Blatter and will announce in August a decision on whether he will run, he said.
"In the future I will not support him (Blatter) any more," Platini said. "I have told him that. I think FIFA needs some fresh wind."
Asked why he had withdrawn his support for Blatter now, Platini said: "In 2011 he asked for our support and told us it would be his last term."
Asked when he would decide whether to run for the FIFA presidency, Platini added: "I will say it at the draw for the Champions League (on Aug. 28) in Monaco. National associations want me to say as soon as possible."
At the Congress on Wednesday, Blatter made no reference to the allegations and investigation into corruption surrounding the awarding of the 2018 and 2022 World Cups and instead pressed his case to extend his tenure as president.
"My mission is not finished," he told officials from FIFA's 209 member associations at the close of the Congress, held in Sao Paulo on the eve of the opening game at the World Cup between hosts Brazil and Croatia.
"Congress, you will decide who will take this great institution forward, but I can tell you I am ready to accompany you in the future," said Blatter, who has led FIFA for 16 years.
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