Adding script to Gui Texture

I have to gui textures that are arrows, and I want them to become buttons.
I just attached the script to the gui texture in the heirarchy, after I run the game, the script is activated whenere I click any place in the screen and not just on the gui texture…
What might be the problem?

You should use OnMouseDown - Input.GetMouseButtonDown is reported when the user presses the mouse button, no matter where, while OnMouseDown only occurs when the object (GUIText, GUITexture or collider) is clicked.