Though anything is possible, the missing child's ethnicity would be very difficult to determine at a glance.
Rather, her appearance could pass for Afghan, anglo-white, hispanic, middle eastern or say, mediteranean white. Furthermore, based on the photos, she does not appear to wear ethnically distinct clothing.
Though the totality does not prevent a hate motivation, it would seem to reduce the possibility as the potential hater would first have to establish that she was a member of the targeted group. Then factor in that individual small children are rarely targeted by haters.
I am thinking horribly of a sexual motive. If that is the case, this increases the chance of the perpetrator being "close to home" and from the same ethnic group as the victim.
Being from the same ethnic group facilitates communication and familiarity between the perpetrator and the victim. Statistically (from what I have seen) most sexual predators prefer their own ethnic group as that is whom they are most comfortable with.