Opponents of the airport project, which is supported by Prime Minister Jean-Marc Ayrault, a previous mayor of Nantes, say it will damage the biodiversity of the surrounding countryside.
Along with farmers who have been evicted from their homes in the area, many squatters claim the temporary buildings are their primary residences.
Anti-airport activist Isabelle Michel told RFI that an eviction order is still being challenged in court, so police cannot legally start tearing down the structures.
The court, in the Brittany town of Saint Nazaire, ruled against an attempt to make farmers who have been evicted pay for the destruction of structures built on the land since the protests started.
A new demonstration against the airport is to be held next Saturday and squatters threatened protests throughout France if they are evicted.
President François Hollande's newly appointed special envoy on the environment, Nicolas Hulot, on Wednesday came out against the airport and called on the authorities to back down.
Hulot, a popular TV presenter who made a bid to become the Green party's presidential candidate this year, said it was inconsistent to call for a reduction of greenhouse gases and sacrifice 1,700 hectares of farmland for the sake of air transport.