I would say... yes. You could argue that he's just being ignorant as to the four women's history, but being ignorant and making a bad assumption based upon their race doesn't mean it isn't racist. You could try to argue that he had other reasoning to make that assumption, but I don't see what it would be.
Although, to be honest... I care more about how Trump decided to paint these women as un-American in his statement. It's not only disrespectful, disingenuous, and unbefitting of the highest power, but I'd be a little worried about what sort of unhinged folks are lapping this up. We're in such an awkward time these days with events like "PizzaGate" where rumors and notions go unchecked, and eventually, one misinformed person snaps. You may not care for their policies... you may consider them brash... but I'm sure most (if not all) people here don't think they should be painted as "the enemy".