It does seem unwise. Rioters are only a tiny part of the entire protest, but they do get much of the attention.

If anything, threats like these will only embolden both peaceful and violent protesters. Does he really believe that this would calm things down or is he planning on inciting more unrest so that he can stage a crackdown? Looking at French history - even just since after WW2 - this rarely went well for those in power, so this would be a risky tactic.

Then again, he appears to have remarkable political instinct and an excellent ability to form and maintain alliances or else he would have long since been kicked out of office, given the enormous domestic political pressure he's been under for years - often, but not always, for good reasons, given for example his efforts to erode the French welfare system.