France's strategy on integrating its Muslim population is not effective. Instead of helping Muslim citizens assimilate, France corrals them into urban ghettos where poverty breeds extremism, and then that extremism manifests itself as violence against the state. Banning the foreign financing of mosques only serves to divide the population even further by making Muslims feel even more disenfranchised than they previously did.
It shouldn't spawn more terrorist attacks because muslims should understand why this policy is being looked at and they should take action to stop other muslims becoming radicalised. Muslims practice in mosques and yet time and again the mosques always say things such as, "Don't blame us, we didn't know". Which is not acceptable with such a serious issue. Perhaps actions like this will make them realise they can't do what they want and have to be scrutinised unless they play their part in cracking down on such horrendous acts of terror. As for those who want to attack, they will do it anyway, regardless of foreign funding or not.
Terrorist activity will not increase if the French government passes a law under consideration that wold ban the foreign financing of mosques. This comes in the wake of a wave of terrorist attacks. France has been known for its tolerance and acceptance of people, including Muslims. Radicals have taken advantage of this to launch attacks.
The terrorist are going to attack anyway and their sites are squarely on France for some reason. I'm not sure if any of the terrorist have ever read the Quran. They are focused on hateful rhetoric and ideology. They are too disenfranchised to care what the government is doing to stop them. I'm sure there are cells already in place waiting to make their next hit.