The 37-year-old actor posted on Instagram that she might need to cut back on her diet after indulging in some homemade food.
"Masseuse just pointed to my stomach and said 'Baby?' Ummmm no... No baby in my belly. I blame Eva Longoria's delicious home-cooking for this," Munn posted.
"I guess I'll start my New Year's diet today," she added.
The actors had earlier celebrated Christmas with each other in Miami along with other friends, tennis star Serena Williams and Gabrielle Union.
Longoria is expecting her first child with media mogul husband Jose Antonio Baston.