If these were Muslim women who normally worshiped at that mosque, the police had no business becoming involved. Since they were Muslim, it seems it'd be hard make a case for trespassing unless they had been told previously not to come on any part of the property. Probably not enough information.
Religions have a right to set their own rules—on private property. Orthodox Jews, and even a few Christian groups (the Amish perhaps? some of the Eastern Orthodox?) traditionally separate men and women in worship—as Muslims always do.
If homosexuals came into your Church dressed in drag...attempting to disrupt your service, don’t you have the right to call the police and have them removed?
These women were doing the same kind of protest—as the main prayers in Mosques always separate men and women. When the women refused to follow the rules (even though you and I don’t like Islam’s rules here) they became trespassers, and the Mosque had a right to expect the police to remove them (just like police should remove any protestors from any religious or private property).
We should be concerned about the many Mosques on American soil which preach violence against the government—NOT the ones that simply rely on the same law we all expect to rely on.