ANSWER:

You must minimize your communication to them to the bare minimum and be as straight as possible with few words without reciprocating with them even if they accuse you of being rude. Lower your gaze and show them lack on interest and do not socialize with them. 

They will get the message loud and clear. 

Shaykh what to do when your in a kafir country and you work in a partially mixed environment where there is some mixing and the females sometimes try talking to you asking questions like “what time do you finish” or “how are you” and you feel as if you will be disrespectful if you just ignore completely, also what about muslim women, what to do?