Hmm, this can be tricky. I think that confronting a group of people in a calm manner and telling them, “I’m not going to play the blame game and point fingers toward who may have started it. That’s not the point as I understand that we all can sometimes get carried away with our words without realizing the potential gravity of them. It has come to my knowledge that there are certain rumors going around about me. I’m not going to say who disclosed the information. I’m only confronting you people directly to put those rumors to rest as you’ll be hearing it from the source…or from the very person that the rumor was about.” (Then make the clarification).
^During this confrontation…letting the people know that you’re not “pointing fingers” and that you’re not going to disclose the name/s of the suspected culprit/s…shows others that you are the “BIGGER PERSON”…who doesn’t want to instigate or fuel further drama. Not shaming the offender…can perhaps elevate you in the eyes of those who heard the rumors. It may even shame them for participating in the gossip either actively or passively.
^Being aggressive…*might" confirm any negative views that people may uphold about you or may have encountered in the rumors.
Apart from that, I think it also depends upon the rumor. If someone has said something unsavoury about your character…and you feel that silence is synonymous with acceptance…and if you feel that making a mountain of the issue makes you look bad as well…then how about a more indirect but active approach???
For example (minor example)…rumor around the workplace is that you’re selfish and inconsiderate. Instead of remaining silent or making a molehill mountain…how about pretending you don’t know about the rumors and acting helpful and friendly toward colleagues? ACTIONS speak louder than words…(and this includes the words of the gossiper). Your positive actions could contradict the negative rumors going around about you. Your actions can help to refute and quell the rumors. Keeping that in mind…they also have the power to fuel them.