The soccer ace was asked by a mystery lady if he would mind performing the unusual act when the pair were in an elevator together at a New York hotel.
A source told National Enquirer magazine: "This woman boarded the elevator, saw David, got all delirious and then - acting like Victoria wasn't even there - leaned over and said, 'I'm pregnant... Could you rub my stomach so that maybe my unborn child will become a famous athlete like you?'
"Before her man could answer, Victoria snapped, 'You have got to be kidding! Do you know how many times women like you try that line? And look at you - I doubt you're even pregnant."
The woman didn't get her wish as the showbiz couple left the lift without her request being granted.
Victoria is currently believed to be trying to put on weight in an effort to get pregnant with a fourth child for her and David, with who she already has Brooklyn, 11, Romeo, seven and Cruz, five.