A Microsoft executive was quoted in an interview as saying "what we've tried to do with Windows 7...is create a Mac look and feel in terms of graphics".
The comments, by partner group manager Simon Aldous, appeared in UK computing trade magazine PCR.
Microsoft countered that Mr Aldous was not involved with the development of Windows 7.
Microsoft's Brandon LeBlanc said in a blog that Mr Aldous's comments were "inaccurate and uninformed".
Suggestions that Microsoft has borrowed technology ideas has been rife for as long as the Windows and Mac operating systems have been around.
The very idea of who invented the "windows" on a "desktop" in Windows 1.0 was the basis of a 1988 lawsuit and remains a point of contention.
'One of our own'
However, many of the significant graphical changes present in Windows 7 have analogues in Mac's OS X - although neither firm has made an official statement about the apparent similarities.
"One of the things that people say an awful lot about the Apple Mac is that the OS is fantastic, that it's very graphical and easy to use," Mr Aldous told PCR.
"What we've tried to do with Windows 7 - whether it's traditional format or in a touch format - is create a Mac look and feel in terms of graphics. We've significantly improved the graphical user interface, but it's built on that very stable core Vista technology, which is far more stable than the current Mac platform, for instance."
Mr LeBlanc countered the claims in a post on the official Windows blog.
"Unfortunately this came from a Microsoft employee who was not involved in any aspect of designing Windows 7," he wrote.
"I hate to say this about one of our own, but his comments were inaccurate and uninformed."