In the West, it seems unavoidable for a Muslim man to look at the face of a non-Muslim woman. How should one behave if looking at the face of such a woman causes lust or attraction?
Looking at the face of a female which causes lust or attraction is definitely not permissible in Islam. Muslim man must avoid any looking which causes lust or attraction. Lowering gaze is obligatory on Muslims as we read in Quran (Sura 24, Verses 30 and 31.
Wassalam.