Maybe on fancy transmissions, but the Citroen I used to drive certainly didn't. Never tried at 100km/h, but I did sometimes accidentally switch to the wrong gear at lower speeds (like switching to 2 or 3 while driving 80) and it never stopped me.

You can always force it ... but in general there is some protection that at least makes a lot more difficult to move to 1st/2nd when doing 100 km/h. Third and fourth are no issues.