CONMEBOL's intervention comes ahead of a FIFA executive committee meeting later this month which is poised to discuss whether to delay the February 26 emergency presidential election.
FIFA's ethics committee imposed a provisional 90-day ban on Platini on Thursday after a payment the UEFA president received from the world body became embroiled in a Swiss criminal investigation.
Blatter, who was also suspended from his role as FIFA president, filed an appeal Thursday with the organisation he has led for 17 years.
Platini was quick to receive the resounding backing of his European confederation on Thursday and now CONMEBOL has denounced the former France captain's ban as "untimely and disproportionate."
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"The presumption of innocence is a fundamental right that has to be considered," CONMEBOL said in a statement on its website.
"Mr. Platini has not been found guilty of any charge, therefore the provisional ban jeopardises the integrity of the electoral process to the FIFA presidency, of which Mr. Platini is a candidate."
"(CONMEBOL) urges that the provisional ban imposed upon Mr. Platini be reconsidered, and that Mr. Platini be allowed, with full guarantees and without impairing his rights, to continue as FIFA presidential candidate," the Paraguay-based confederation said. "These are trying times that demand an integral reform of FIFA.
"(CONMEBOL) fully believes in Mr. Platini's capacity to lead FIFA and the football world towards a brighter future."
Although FIFA quickly named an acting president - Issa Hayatou - as required by its statues, UEFA has not elevated its senior vice president - Angel Maria Villar - to temporarily fill Platini's job.