A Putsch is a small uprising or rebellion with the purpose of changing a government or way of leadership. It can be an armed action, but it may also be other type of guerilla actions aimed at rising awareness for a particular issue.
Getting 10 people to suddenly run into the street and block off the entire Arc de Triomphe Rond-Point (roundabout) wielding political banners, for example, may be considered a Putsch, even though its goal doesn't necessarily have to be a coup d'etat.
A short, targeted worker's strike (such as when the London metropolitan police marksmen refused to carry firearms for a day, following a court ruling that a killing had been unlawful) may also be considered a putsch, especially if the action comes relatively unexpected.
One of the more famous Putsches in history is the Beer Hall Putsch, by Adolf Hitler, aimed to overthrow the Weimar republic in November of 1923