The 'What Makes You Beautiful' singer said that he had imposed an age limit on his love life after breaking up with Caroline Flack, who at 32 is 14 years his senior.
Despite previously saying that "age is nothing but a number", Styles was quoted by Metro as declaring at a Brit Awards after party: "I'm through with older women."
The boyband member confirmed his split from Flack in January, though they continued to be romantically linked.
Referring to inaccurate reports that the couple were still together, the Xtra Factor host wrote on Twitter: "Note to some people/mags ... You are still speculating over something that clearly finished a while ago... Leave it now.. Please."
Styles has recently been spotted out with Georgia May Jagger - the model daughter of Mick Jagger - and Pixie Geldof.
Watch One Direction in the video for 'What Makes You Beautiful' below: