Green, 36, and Grant, 30, attended the Tarina Tarantino Sephora launch party in Hollywood Wednesday and were seen cuddling at the valet stand, but were tightlipped about details of their upcoming nuptials, according to E! News. A source tells PEOPLE that despite reports, the couple did not get engaged on New Year's Eve.
Green is the executive producer and co-creator of Robot Chicken for which Grant also does voice-overs. The actor, who was an original cast member of Family Guy, will next appear in Disney's Mars Needs Moms.
Grant, who attended the University of Memphis, appeared with Christina Ricci in Black Snake Moan and stars in the new MTV series $5 Cover.
With reporting by CYNTHIA WANG