Quran says..
There are several forms of lying to non-believers that are permitted under certain circumstances, the best known being taqiyya (the Shia name). These circumstances are typically those that advance the cause of Islam - in some cases by gaining the trust of non-believers in order to draw out their vulnerability and defeat them.
Quran (16:106) - Establishes that there are circumstances that can "compel" a Muslim to tell a lie.
Quran (3:28) - This verse tells Muslims not to take those outside the faith as friends, unless it is to "guard themselves" against danger, meaning that there are times when a Muslim may appear friendly to non-Muslims, even though they should not feel friendly.