Cooper, 37, and Zoe Saldana, 33, worked together on the upcoming thriller "Words."
They were first seen kissing at a New Year's Eve party, but sources said their relationship was short-lived.
"They're definitely not together," an insider told UsMagazine.com Wednesday.
"She and Bradley weren't super-serious at all," another friend said.
Best known for his work in the "Hangover" movies, Cooper is People magazine's current Sexiest Man Alive title holder.
Saldana has starred in the films "Avatar" and "Star Trek."