Ooo... that's a small tank.
Nonetheless, all tetras have different temperaments. In a bigger tank, all tetras will pretty much get along with a few minor scuffles/chases. It's normal.

In your small tank keep an eye out on the fish and make sure they don't cause too much harm to each other.

Head and tail lights are already amoung one of most placid tetras (OK, the neons are the most placid, but H&T tetras aren't far behind.). If you're already facing problems, I suggest you stay clear of Serpae tetras or black widows as they can be more nippy. Also, in a small tank like yours, Tiger barbs would be a BAD idea as well.

Stick with placid fish like neon tetras, cardinal tetras, rummy nose tetras...