According to Life & Style, the Coming Home rapper and Diaz were seen sharing a passionate smooch at the Big Apple's Dream Downtown building last weekend.
Eye-witnesses told the publication that Diddy and the Bad Teacher actress were "making out like teenagers" - fuelling reports that they're an item.
The couple, who were said to be casually dating earlier this year, have previously dismissed rumours of romance, insisting they were only meeting up to discuss film projects.
Speaking of Diddy - real name Sean Combs - a friend of the star previously stated that he was always "single whenever there's a better offer on the table."
Watch MTV News on the hour every hour on MTV - Sky Channel 126 and Virgin Channel 134