Is there a sin upon one who claims a vision, a dream, and an interpretation that did not occur, by way of advice to avoid causing problems?

Advice is a great act of worship, and the Prophet, peace and blessings be upon him, made the entire religion advice. You have done well by being keen to advise the girl, but your choice of method was wrong, because what you did was plain lying. There are legitimate ways to advise without lying, such as an anonymous letter. Lying in a dream, in particular, has been forbidden, so do not repeat such an act.