From 1st October this year it has become compulsory that certain disputes between neighbours must first try to be solved amicably before going to court.
This applies to claims not exceeding €5,000, to unusual or abnormal disputes and also complaints relating to boundaries, tree pruning and the like. Mediation can be handled via the courts or you can appoint a lawyer to act on your behalf.
You can also appoint any neutral third party to represent you – in smaller rural communities the local mayor can be a good starting point.
You can see details concerning the procedures
https://www.service-public.fr/particuliers/vosdroits/F1732
https://www.service-public.fr/particuliers/actualites/A16778