The French football legend told AFP on Tuesday that he had done "nothing wrong" and defended a $2-million payment approved by Fifa president Sepp Blatter.
Platini, who had been favourite to win an election for the Fifa president in February, spoke out amid reports that he and Blatter will soon be put under investigation by Fifa's independent ethics committee.
"I am still determined to present myself as a candidate for the Fifa presidency so I can introduce the governance reforms that are necessary to restore the order and credibility to world football," Platini told AFP.
Swiss prosecutors say they are investigating whether Blatter approved a "disloyal" two million Swiss franc ($2 million) payment to Platini, to Fifa's prejudice.
The money was paid for work carried out between 1998 and 2002 but the payment was only made in 2011.
The Frenchman, who has led UEFA since 2007, said the delay was because FIFA could not afford to pay him earlier.
"There is no doubt about my integrity. I have done nothing wrong. That is why I have made myself fully available to cooperate with the relevant bodies and authorities to clarify whatever may be necessary," he said.
"I was employed by FIifa as a special advisor to president Sepp Blatter, working on various matters related to football, such as the international football calendar. It was a full-time job," Platini said.
'FIFA could not pay'
"Like I explained to the Swiss authorities, I received only part of the agreed salary between 1998 to 2002.
"This occurred because, at the time, Fifa informed me that they would not be able to pay me the total agreed amount."
Platini said all of the money received was "declared to the pertinent authorities."
The 60-year-old Frenchman said he did not fear a suspension by the Fifa ethics committee "because I have done nothing wrong."
"I am calm and totally serene since I don't have reasons to be concerned," said Platini who said he had received messages of support from around the world.
"I have known for a long time that I would be the target of many unfounded attacks and I am conscious that these attacks will continue until the Fifa elections take place."
Switzerland on Tuesday ordered the extradition of another fallen Fifa official and the world body's ethics committee ordered a life ban from
football against former vice-president Jack Warner.
But South Korean tycoon Chung Mong-Joon, a rival candidate to Platini in the Fifarace, called for a task force to run Fifa because of the "total meltdown" at the world body.
He said Fifa should organize an "emergency congress" to set up the task force leadership.
"The most urgent task at hand is to root out corruption from within Fifa," he said.
"Justice must be served."