The 32-year-old former Arsenal and Barcelona midfielder was one of nine players who were sacked last week for refusing to take pay cuts amid the coronavirus pandemic.
Club captain Xavier Kouassi, former Newcastle loanee Seydou Doumbia, Ermir Lenjani, Mickael Facchinetti, Christian Zock, Pajtim Kasimi, Johan Djourou and Birama Ndoye also had their contracts cancelled.
Like most leagues around Europe, the Swiss Super League has been suspended due to the Coronavirus pandemic since March 1 with 13 games still left to play.
Song told French broadcaster RMC: "My lawyer will take care of it, it's gone to FIFA. We're going to defend our right.
"We played a friendly on Friday and we were supposed to meet with the president on Monday, then Tuesday. We had no news.
"We received a WhatsApp message on Tuesday afternoon to tell us that everyone had to sign a paper saying that we'd reduce our salaries, that we'd be paid around 12,000 euros.
"We had to return the paper by 12pm the next day. We received this document without an explanation."
He added: "We decided together to not sign this document. We wanted to discuss it.
"I've not committed any professional mistake. Every club talks to their players to reach solutions.
"I don't understand what's happened. Nobody can understand it."
Over 14,500 people have tested positive for the virus in Switzerland, including the country’s football association president Dominique Blanc, while 300 deaths have been recorded.
