A Fifa spokesman said it had received a formal "intention to appeal" from the AUF on Friday night and that the Uruguayans now have seven days to submit their written reasons.
Suarez was banned last Thursday for Uruguay's next nine competitive international matches and from any involvement in football for four months after biting defender Giorgio Chiellini in his side's 1-0 Group D win over Italy.
It was the third biting incident involving the brilliant but troubled Uruguayan, who also plays for Liverpool and led the Premier League in scoring this past season.
The Associated Press reported earlier that Suarez told Fifa's disciplinary panel that he did not deliberately bite Chiellini.
"In no way did it happen how you have described, as a bite or intent to bite," he wrote in Spanish in a letter dated June 25.
The player's defence is contained in paragraph 6 of Fifa's disciplinary committee ruling, which has been seen by The Associated Press.
"After the impact ... I lost my balance, making my body unstable and falling on top of my opponent," Suarez wrote in his submission to the panel.
"At that moment I hit my face against the player leaving a small bruise on my cheek and a strong pain in my teeth."
However, the seven-man panel which met on Wednesday evening dismissed the argument.
The bite was "deliberate, intentional and without provocation", the ruling stated in paragraph 26 of the panel's conclusions.
The panel, chaired by former Switzerland international Claudio Sulser, included members from the Cook Islands, Hong Kong, Pakistan, Panama, South Africa and Singapore.
The ruling confirmed that referee Marco Rodriguez of Mexico acknowledged in his match report that he missed Suarez's bite. So did his two assistants and the fourth official.
"I haven't seen the incident because the ball was in another sector of the pitch," Rodriguez writes in paragraph No. 4 of witness submissions in the 11-page document.