The 23-year-old singer was left red faced earlier this week when the 'Bon Appetite' hitmaker revealed he is ''always'' trying to get her phone number despite their nine year age gap.
She said: ''I see him around all the time, he's always trying to like get my number to like maybe flirt with me but I'm like 'I could babysit you I'm like your mum!'''
And the 'Slow Hands' hitmaker says his natural ''Irish charm'' may have made his harmless invitation of friendship seem like more than it was, and joked he feels ''embarrassed'' by the whole situation.
Speaking to Australia's Daily Telegraph newspaper, Niall said: I don't know if it's in the accent or the way we put things but I guess that stigma of Irish charm follows you around a bit, which is not a bad thing really.
''I don't know what [Katy's] talking about, by the way. I texted a mutual friend who works on her team saying, 'I heard you guys are going to be down in Australia'. Katy has taken that and run with it and embarrassed me in front of the whole world.''
The comments come after the One Direction hunk jokingly urged the 'Chained To The Rhythm' singer to ''stop being mean'' to him.
He said: ''Katy, please stop being mean to me! She is just finding any excuse to just patronise me and go around spreading rumours about me. I just want to be her friend.''
Meanwhile, the 'This Town' singer previously said he's in no hurry to settle down with anyone as he's ''flat out busy'' with his solo career and doesn't think a relationship will ''fit in'' with his hectic schedule.
When asked about his love life, he said recently: ''I've been flat-out busy and kind of went through a stage of not caring about it for a while and I'm going to be busy now for the summer again.
''So I don't really know where I'm going to fit that part in. But if it happens, it happens. I've got many years ahead for that.''
Many ticket-holders couldn't get into the O2 Arena show on Tuesday night (September 19th) because they didn't bring photo ID to match their booking.
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