French forward Sebastien Chabal must referee at least three youth games and undergo a refereeing course to avoid a doubling of his 30-day ban for criticising officials.
Chabal, 33, the highest profile omission from France's World Cup squad announced on Wednesday, was provisionally suspended by his Racing Metro 92 team last month after an outburst against "hopeless" referees.
The long-haired back-rower now faces a 60-day ban unless he agrees to the unusual requests from the union, in which case he will be suspended for only 30 days.
The ban comes into effect from Thursday, even though Chabal has already served a two-week ban imposed by his club Racing-Metro since describing Top 14 referees as "useless" in an interview.
That means that Chabal will miss the Top 14 play-offs, in which Racing are due to play either Castres or Montpellier in Marseille on May 28.
On Wednesday France coach Marc Lievremont left the 33-year-old Chabal out of his World Cup squad, saying his decision to do so was based entirely on performance.
But Racing coach Pierre Berbizier said he believed Chabal was being punished.
"I am surprised and sad for Sebastien," he said of his omission.
"He has paid for his comments about referees. He is the victim, not of sporting performances, but of the parasites that surround him and prevent him from concentrating solely on rugby."
Media reports have speculated that Chabal could announce his international retirement after Wednesday's snub for the September 9-October 23 tournament in New Zealand.
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