An article in a recent edition of In Touch alleged that Marshall Green proposed to Tomei while they were celebrating the holidays.
A spokesperson for Tomei has now clarified to E! News that the Oscar-winning actress has no plans to tie the knot.
"There is no truth to the rumour," Tomei's representative said.
Marshall Green and Tomei were initially linked in 2008 after they worked together in a theatre project in Los Angeles.
They have since appeared at many red carpet events together.
Tomei previously dated Iron Man 3 star Robert Downey Jr and Lenny Kravitz earlier in her life.
Watch a clip of Marisa Tomei in Parental Guidance below: