Absolutely not when you don't even know the bride!
A very close friend or a relative, you could ask - but it's far too risky to clash with either bride or bridesmaids.
Bridal wear is so much more varied, you have absolutely no guarantee what the bride will chose. And as a guest you have all the colours of the rainbow, why picking white!
I can't be bothered to search through wedding dresses, but the photo attached is a bridal dress....You'd clash already.