nanna8
I have never heard that one ( peaceful). It could be interpreted as meaning you are a belligerent type or you had been involved with something causing strife and personally I wouldn’t use it.
Well, on that basis - although it's the norm - I could interpret people wishing me a "happy" new year as meaning they think I'm rather miserable. 
In fact, as well as saying "peaceful new year" to others - I've had it said to me. And I saw a pack of Christmas cards wishing a "joyous" and "peaceful" Christmas.
I think, in the wider sense, it means 'mellow' or 'restful'. And it's gaining currency I believe because a large part of the world - and particularly here in the UK - there's unprecedented (apart from two world wars) turmoil. As another delivery driver said to me - "well, next year's gonna be much the same as this one, innit?"