I can't speak for France, but here in Italy it is normal to have a small amount / fee added to your bill when you eat in restaurants. As Mouviciel says correctly, it is something you pay to have a seat at the table, with all the necessary things.
Although it is true that normally it is just 1.50 / 2 euros, it is also true that the amount of the "fee" depends on the restaurant (I think I've seen it as high as 5 euros per person). Expect to see it added to your bill in pizzerias, restaurants and "trattorias", whereas you won't be asked anything extra if you eat in a self-service restaurant, in a café where they serve sandwiches and ready-made dishes, especially at lunch time for office workers, and normally places which offer "exotic" food (Japanese, Mexican, Indian, etc.) do not charge it either.