Article 673 of the Civil Code provides that the owner of a land on which "the branches of the trees, shrubs and shrubs of the neighbor may advance may compel the latter to cut them". Your neighbor is therefore legally obliged to prune his tree.
Attention: You do not have to do it yourself. In case of inertia on the part of your neighbor, you can send him a registered mail with acknowledgment of receipt.
If it does not execute, you can appeal to the court of first instance. The court may provide that in the event of refusal to comply within the time limit set out in the judgment, the applicant will be allowed to make the size at the expense of the owner of the tree.