Nope,it doesn`t.
`Sensei
Q. My opponent has a R/S Dustox active (or on the bench); I play a Sandstorm Omastar and use Pull Down; does this attack effect Dustox or not?
A. No. Dustox's Protective Dust prevents all effects done to Dustox, by the opponent's Attacking Pokemon - this woud include Omastar's Pull down.(Oct 2,2003 PUI Rules Team Meeting)