Gwede Mantashe said the party is deeply concerned by the problems facing Cosatu and its affiliates.
Unions say the legal papers will force Cosatu into convening a special national congress.
Cosatu leaders will meet today without the participation of 7 unions that are opposing Numsa's expulsion.
Numsa says if its challenge fails, it will look elsewhere to ensure workers are protected.
Irvin Jim said the decision to expel the union was due to individual agendas.
Cosatu's national leaders say they've decided to try and find solutions to the federation's problems.