In Christianity, God is called the father in part because He is the creator that created all the beings and because of God's active interest in human affairs, the same way that a father would take an interest in his children, acting in their best interest and punishing those who misbehave. In Islam the concept of God being the father is not accepted because there is a difference between the father-son role and God's role. God is our Lord and Creator; we can't compare Him to any earthly life and expression such as family concept. We are created to worship Him and serve Him alone.
Indeed this, your religion, is one religion, and I am your Lord, therefore worship Me (Alone).
God is our Lord, He rewards who He wishes and punishes who He wishes, and if we believe in God's majestic control and power on us, could we then compare that to earthly life. Say for the sake of argument that God is like our boss (God is exonerated from such a comparison) since the boss rewards us for our work and punishes us if we don't accomplish it? If so, do we consider or call our boss, our father? We do not because he is not our father.
And (both) the Jews and the Christians say: "We are the children of Allah and His loved ones." Say: "Why then does He punish you for your sins?" Nay, you are but human beings of those He has created, He forgives whom He wills and He punishes whom He wills. And to Allah belongs the dominion of the heavens and the earth and all that is between them; and to Him is the return (of all).
God gives us choice and according to that choice we are tested, we either fail or succeed. While the father figure will try his best to lead his children to be like him or even better, nothing is better than God. Therefore, there is no comparison between God's role and a father's role.