Argentine league champions Estudiantes are struggling at the bottom of this season's Apertura with 10 points from 14 matches and can ill afford to lose a key forward for that length of time.
Tigres wanted a heavier sanction for Fernandez over breach of contract after he left them in January 2010 to return to Estudiantes, for whom he had scored the equaliser when they beat Cruzeiro of Brazil 2-1 in the 2009 Copa Libertadores final.
"We can confirm that within the scope of a dispute opposing the Mexican club Tigres de la UANL to the Argentine player Gaston Nicolas Fernandez and the Argentine club Estudiantes de la Plata, on 7 September 2011 the Dispute Resolution Chamber (DRC) passed its decision to, inter alia, ban the player in question from playing in official matches during a period of four months," the world governing body said in a email to Reuters on Monday.
"The relevant decision was notified to the parties concerned on 15 November 2011."
Tigres President Alejandro Rodriguez said last week his club, whom Estudiantes must also pay a $600,000 fine, were unhappy with what they considered an insufficient sanction and would appeal.
"We're not in agreement with this resolution," he said.
"We lost much more in terms of the investment we made in Mr Fernandez, the impact of the moment [he moved away] which was a week or 10 days before the [2010 Clausura Bicentenario] tournament started. These are damages we are fighting... because we believe the sanction is very low."
Tigres signed the 28-year-old "Gata" (cat) Fernandez for $3.5 million from San Lorenzo in 2008 and he was on loan to Estudiantes when he helped the Argentine side win their fourth Copa Libertadores in July 2009.
Back at Tigres but unable to hold down a place as one of the Mexican club's permitted foreign players, Fernandez decided to leave just as the Clausura, second championship of two in the Mexican season, was about to start in January 2010.
FIFA gave Fernandez a temporary international transfer document so he could play for Estudiantes again but Tigres kept their case alive with the DRC which finally handed down its sanction last week.
Although FIFA did not specify when Fernandez's suspension should start it is expected to be from the beginning of the Argentine Clausura championship in early February.
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