(little) white lie
A lie thought to be insignificant and justified, especially one told to avoid hurting someone's feelings or giving offense. I try to be honest most of the time, but I do tell white lies when I'm worried about upsetting people. A: "Do you actually like her new haircut?" B: "Of course not, but I couldn't tell her that, so I told a little white lie instead."
little white lie
Fig. a small, usually harmless lie; a fib. Every little white lie you tell is still a lie and it is still meant to mislead people.