Fuimaono-Sapolu had breached the Rugby World Cup/IRB code of conduct following his rant about referee Nigel Owens on Twitter.
The 30-year-old had accused the Welshman of bias after Samoa's tournament-ending defeat against world champions South Africa.
Fuimaono-Sapolu's sentence has been suspended for two years, pending three conditions - he makes a full and unconditional apology to Owens and unconditional retraction of any criticism of him; carries out minimum 100 hours' rugby community work in Samoa in support of the IRB's high performance programme within the next 12 months; and attends and passes a recognised referee course within the next three months.
Judicial officer Judge Jeff Blackett determined that the comments made about Owens by Fuimaono-Sapolu "impugn his integrity and reputation, both as a referee and as a man".
And although Blackett said he recognised the Gloucester centre might have been angry or emotional when making his initial comments on Twitter, it did not justify his offensive behaviour towards the referee.
Contrary to the Fuimaono-Sapolu's submissions, Blackett said there was "absolutely no evidence that the referee was biased in the sense that he deliberately favoured one side or the other.
To suggest that Nigel Owens is racist against Samoans is also completely inappropriate".
Fuimaono-Sapolu, who had already been warned by World Cup chiefs about remarks he made on Twitter earlier in the tournament, has the right of appeal.
Fuimaono-Sapolu Tweeted after the hearing: "I do not want to play rugby anymore. One thing is for sure, my children definitely won'.
"I'm so grateful and so overwhelmed with the many people who were at the hearing today. Thank you beyond what my heart can give. Love you all."
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