In his Mishneh Torah -Issurei Biah 1:13, Rambam states that if a male copulates with a girl under the age of three,also the male,even if he was an adult, is exempt from liability, for the act is not considered as sexual relations (this is because the girl's hymen will grow back).
In Mishneh Torah-Naarah Betulah 1:8, Rambam says that if a male (also adult) rapes a girl under three years of age, there is no payment of the 50 sela'im of pure silver, as the relations are not significant ; Rambam also states that, when this fine is provided, the raped girl is also entitled to compensation for embarrassment, damages and pain, while if no such fine is provided, the raped girl has no right to compensation for embarrassment and damages ( Naarah Betulah 2:10).
In the event that a Jewish adult male rapes a Jewish girl under three years of age, according to Halakhah, is the male sanctioned or not? He cannot receive lashes de'oraita, and he is not required to pay the fine of 50 sela'im of pure silver. According to Rambam (see above), he is not required to pay compensation for embarrassment and damages: is he obliged to pay compensation for the pain caused to the little girl? This is not clear to me from the above passages of the Mishneh Torah.