Key told Newstalk ZB all is not what it seemed over his reported comments and he didn't owe anyone an apology.
Talking to Mike Hosking, he again would not deny the "batshit" comments and would not be drawn into discussing the issue.
"It's probably not quite the way you see it in the paper. It was a private conversation, I was talking to a few people and that's what he thought he heard."
Key allegedly made the comments about the LA Galaxy midfielder while talking to students at Dunedin's St Hilda's Collegiate on Friday, according to a Radio New Zealand report.
The story has been widely reported on in the UK, but also in Australia, the US, India and Malaysia.
Britain's best-selling tabloid newspaper The Sun led with the story.
"The PM said Becks, 37, had been very friendly, but then cruelly claimed that the LA Galaxy star wasn't particularly bright," Gary O'Shea wrote.
Read more:
'Thick as bat shit' remark gets brush-off from Beckham camp
PM less than impressed by Beckham's brain
- nzherald.co.nz