Work related question

I have recently started work in a new place and work wise have had no bad feedback at all. Whoever one of my coworkers has been telling lies about me (wanting my managers position) not true whatsoever. I have asked confrontation with her but the manager dose not think that is a good idea, instead we should just pretend nothing happened and carry on with our day. I am finding hard to coop emotionally throughout the day. Any suggestions what is best for me to do, this has never happened to me? Thank you in advance