The mother-of-one reacted angrily to the suggestion she'd hooked up with Michelle, which came just a few days after Evan announced her separation from husband Jamie Bell.
Evan had been on a "Twitter break" since her marriage split was announced, but returned to the social networking site over the weekend to lambast stories of a Michelle flirtation.
"Looks like someone is already trying to start a rumour that I hooked up with Michelle Rodriguez at an evening with women," wrote Evan.
"I have never even said hello to Michelle Rodriguez. I think it's convenient someone chose to make up the story now and not that night."
Evan then shared a YouTube video of herself leaving the event in question, posing: "If a 'source' saw us leave together, why am I seen here leaving alone?"
She then added: "Also, just because you are in a photo with some doesn't mean you spoke or slept together. Really, guys?"
Evan also retweeted comments from her fans, including one who suggested the hook up rumour had started simply because Evan had been open in the past about being bisexual.
Actress Evan and actor husband Jamie announced their split at the end of May, following two years of marriage. They are parents to a son, born last year, but have never made his name public.
Michelle, meanwhile, has most recently been linked to model Cara Delevingne.
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