It has nothing to do with your physical sex, but I do not wish to strike you. The First Law of Robotics states that a robot must not harm a human, nor through inaction, allow a human to come to harm.

[It's not that straightforward. It never is. He's harmed humans to protect greater harm to other humans; it's all a system of weight and comparison, the path of least possible harm. And even if he's gone so far as to formulate one more Law that goes before the First, it still holds, regardless of whether or not he could actually land a hit.]

Merely determining my own strength, which I know, is an insufficient reason to take that risk.