How to handle button OnClick event along with Input.GetMouseButton(0)

Hi there,
I would appreciate your help/hints on the following matter:
I have a panel at the bottom of the screen with a couple of buttons. On the other hand, since this is a mobile game, I basically process Input.GetMouseButton(0) in my player FixedUpdate method.
The issue I have - when I click on a button, the click is also propagated by player FixedUpdate method, which is undesirable.
So my question is - how can I process OnClick only and stop propagating the event to Input.GetMouseButton(0) when the user clicks over the button? Alternatively - if the implemented approach is not the right one, please suggest the better one to handle the case.
Thanks!