We already know what are the reasons given by France for the attack toward Spain. But how do they say in England about these matters ? "Fishy" ?
Fact is, it was France to attack Spain and not the contrary. If Spain really threatened France even if clearly not in a position to do so, it would have been quite easier and less costly to just defend the borders to see if really Spain would have attacked (which we doubt).
It is the Emperor's suspect, instead, that France thought it easier to conquer Portugal if holding northern Spain... but this aggressive and expansionist stance form France has now become intolerable to the Emperor, and He asks one last time a cease fire from France and restitution of all conquered provinces as soon as Spain will be able to forgive this horrible sneak attack from France.