Song was fined one million CFA Francs ($2,159) after a disciplinary hearing of the Cameroon Football Federation, state radio reported at the weekend.
Song had been charged along with Eto'o and Tottenham defender Benoit Assou-Ekotto, who did not attend the hearing.
Song, who has not played for his country since a bust-up with captain Eto'o during the World Cup last year, had refused to shake hands with the African Footballer of the Year when the two met ahead of an African Nations Cup qualifier against Senegal earlier this month.
It was the first time that Song, who missed the match because of injury, had returned to the squad since last year's World Cup in South Africa. His disagreements with Eto'o led to him being sidelined during the tournament, in which Cameroon lost all their matches.
Eto'o was found not guilty at the hearing of missing a training session and showing indiscipline during the Senegal match when he disputed a substitution that coach Javier Clemente.
Assou-Ekotto was given an official warning for missing the match without explanation, the radio reported.
The June 4 match ended goalless, effectively costing Cameroon the chance of a place in next year's finals.
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