The pair was linked after they were potted sharing a kiss at Britain's V Festival earlier this month (Aug13).
The Your Song hitmaker has since been bombarded with tweets from obsessed fans of the band, and she insists she has decided against speaking about her reported romance with the Irish singer.
She tells Britain's Daily Mirror, "Oh God, I knew this was coming! I just can't talk about Niall. I won't ever talk about my love life any more because it's always then gone wrong when I have in the past.
"But I will say this, I've definitely had some 'interesting' tweets since the story came out. Thankfully I'm able to take it all with a pinch of salt because I've been told to be that way.
"I genuinely mean this - I don't hate on anyone, but at least One Direction fans are very passionate and my fans are very passionate too. I'd hate it if people didn't care about what they thought."
The singer has previously dated actor Jeremy Irvine, dubstep star Skrillex, and British DJ Greg James.