The 35-year-old claimed in 2004 that she had a four-month fling with the former England captain while she was his personal assistant during his stint at Real Madrid.
The allegations put Beckham's marriage to ex-Spice Girl Victoria, who decided to stay with the midfielder, in the spotlight, despite Beckham denying the story.
"I'm a mother now and married and knowing what I know now I would definitely have gone about things quite differently," Loos told ITV morning show Daybreak.
"I was young and foolish and very reckless. I didn't think things through and acted on impulse a lot. I think I regret the impact on everybody.
"I think I could have gone about it in a kinder way. I don't regret speaking out but I regret the way I went about it."
Loos is now married with two young sons.