Islamic ethical rules are universal values that are not restricted to Muslims dealings with Muslims. Whatever is deemed unethical, is forbidden to practice with Muslims or non-Muslims. And whatever the Muslim is forbidden to do in Islam, he or she must refrain from it whether he or she is dealing with Muslims or non-Muslims.
Lying, of course, is forbidden in Islam; therefore, the Muslim is prohibited to lie to anyone, be he or she is a Muslim or non-Muslim. The Prophet (peace and blessings be upon him) is reported to have said: "Speak truth, as truth leads to righteousness, and righteousness leads to Paradise; and refrain from lying, as lying leads to sinfulness, and sinfulness leads to hell."