He's not out there trying to kill either Cap or Bucky. He uses his repulsors several times and they are blocked with the shield which is why they are tossing it between them. Not to mention he has to actively know what he is doing and aim things, he can't just launch missiles in fixed locations with his mind. Plus we have no context, etc, etc...so I don't know what point in the story this is happening or what condition Tony is in prior or during the fight.
It remains to be seen how far down the comic line they go, so I really just don't have any grasp on what we're seeing to judge it this way. It seems a little over the top I can admit, but I'll reserve final judgment until I see how that plays out. They did a fairly even keeled job on Winter Solider, so I don't expect it will feel unnatural in the movie.