Are they serifs? On serif fonts the bars themselves get serifs. They are more like the bar on capital G or the cross bar on capital A.
If they were "proper" bars that were an integral part of the letterform, then in a serif font there would be crossbars on the uppercase i that would then have ending serifs themselves, such as you find at the top of a T. But obviously those aren't there.
So yes, they function entirely as serifs, not like bars in other letters.