The Hollywood star was apparently spotted with fellow actor Joseph Gordon-Levitt in a New York restaurant last month.
"They were kissing. They were very lovely," an eyewitness is quoted as telling the magazine.
Gordon-Levitt is the 30-year-old star of The Dark Knight Rises, a 2012 action thriller co-starring Christian Bale.
He and Johansson have known each other professionally for some time and were pictured together at the Spike TV awards in LA last year (above, second photo).
But a rep for Gordon-Levitt denied the report of a blossoming romance between the pair. "Joseph wasn’t even in NYC the night that Us Weekly is reporting they were spotted together," he told Celebuzz.
Since separating from husband Ryan Reynolds last year, 26-year-old Johansson has dated Sean Penn and has also been linked to Bradley Cooper.