All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
A father to looking at his daughter with desire, proves that he is debased and that his Fitrah (natural disposition upon which Allaah created mankind) is deteriorated. So, your father is obliged to repent to Allaah and seek His forgiveness. It is known in Islam with absolute evidence that the daughter is among the eternal Mahaarim of the father (relatives whom a person is prohibited from marrying); Allaah Says (what means): {Prohibited to you [for marriage] are your mothers, your daughters, your sisters, your father’s sisters, your mother’s sisters....}[Quran 4:23].
Indeed a sound nature and a sane Fitrah do not permit a person to look at female Mahaarim with desire.
Anyway, one should not suspect his father especially in such matters. Even when this abominable act is confirmed about the father, this does not waive his right of being dealt with kindly and keeping relations with him while taking all the necessary precautions. In such a case, you should prevent him from staying in seclusion with you.
Finally, please refer to Fatwa 86063 about a father who tries to seduce his daughter.
Allaah Knows best.