Wiltord, 33, was dropped from Rennes' professional squad following his public criticism of Guy Lacombe, claiming he was not being selected for non-footballing reasons.
Rennes axed Wiltord from their squad "until further notice" but Fabrice Henon-H
ilaire, the player's legal representative, has demanded his client be recalled.
And he also wants to hold talks with representatives of the Brittany club to find out where Wiltord's future lies.
"I officially contest the punishment that has been applied on Sylvain and I ask that it is lifted immediately," said Henon-Hilaire.
"I appeal to the club to make their position clear as regards Sylvain.
"The good relationship I have with president (Frederic) Saint-Sernin and (general manager) Msr (Pierre) Dreossi leads me to think that Rennes aren't looking to part with Sylvain by these hare-brained ways.
"I hope that we can have constructive talks with everyone very soon. Rennes must accept the consequences of the decision of their coach."
Wiltord joined Rennes from Lyon last summer but has experienced mixed fortunes over the past 12 months.
Since Lacombe joined as coach midway through last season, Wiltord has been mainly used as a substitute.
Former Gunner axed for public criticism of coach - click here