He did not.
The French newspaper Le Monde released an article debunking this claim.
The origin of the quote is a German satirical article from Contra Magazin.
Original quote in German:
Die Briten verstoßen gegen die EU-Rahmenbedingungen, da es nicht in der Philosophie der EU liegt, dass der Mob über Aufstieg und Untergang der EU entscheiden darf.
Translation by leftaroundabout in the comments:
The British are violating the foundational conditions of the EU, for it is not part of its philosophy that the mob gets to decide whether the EU shall rise or fall.
The quote is clearly fictional, as stated in the legend of the picture (In Satira), and at the end of the article (Achtung Satire!)
To find the source of this quote, Le Monde journalists retraced the path it took. They started with the Finance blog Zero Hedge, which made an article about how undemocratic the EU is. The trail then leads to a few Twitter accounts (in order Tale of Two Treaties, Giovanni Zibordi and Professor Werner). Finally, Professor Werner quotes the original article from Contra Magazin.
The article from Le Monde also contains screenshots of the relevant tweets.