You'll be more likely to get a solid answer if you ask about one revolution in particular at a time--there was no single reaction that all European powers took in all instances of revolution. Even a single country did not have one "reaction" per se, but could change and develop according to the greater international politics at foot. For example, after the Glorious Revolution in England, France was very much an on-again, off-again supporter of the deposed monarch and his Jacobite movement, offering him and his court shelter in the aftermath, but kicking them out under the terms of the Treaty of Utrecht that ended the War of the Spanish Succession. But then there was the War of the Austrian Succession, when France allowed itself to be a launching point for a new Jacobite rising, with soldiers pledged.