NEW: President Donald Trump reacts to 9/11 victims' families calling on NYC Mayor Mamdani not to attend upcoming memorial services ahead of the 25th anniversary

NEW: President Donald Trump reacts to 9/11 victims' families calling on NYC Mayor Mamdani not to attend upcoming memorial services ahead of the 25th anniversary of the terror attacks. "Well, I think they're having a hard time with Mamdani. The people having to do with anybody, having to do with 9/1…