Hudson and Bellamy, who are engaged, welcomed their first child, a son, last year.
Hawn sparked wedding-bell buzz when she told Britain's Evening Standard newspaper: "When my daughter Kate married an English rock star it didn't worry me. All that matters is that the relationship is a good one."
But a source close to Hudson told UsMagazine.com Hawn didn't mean Hudson and Bellamy were literally married.
The insider pointed out Hawn has been with her partner, actor Kurt Russell, for decades and refers to him as her husband, even though they have never wed.
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'
Texas principal bans speaking Spanish, stirs controversy