I'd call these des poteaux. Google seems to think the same (going by the pictures that come up when you look up "poteau trottoir").
Bittes (with two T's!) are slightly different. They look like this, and you usually only come across them while walking along harbours. They're used to moor ships to the docks (they're probably called bollards or maybe mooring bitts in English?).
Bornes doesn't work. I might call these "bornes", but I think I'd actually be more likely to stick to poteaux. Une borne is usually either kilométrique, or électronique (in train stations or shopping mall).
Une bitte is a mooring-post on boats and wharfs ( a bollard ) and does'nt refer to anything else ( as a motionless object , I mean ). The word borne can be used for milestones, boundary markers, fire hydrants and certainly for other objects , but not for these kinds of posts.
I think the usual term is un poteau or more technically un potelet.