Mr Greening, who has seven children and is involved with rugby league and union teams, expressed particular concern at changes aimed at beneficiaries.
Under the changes, 18- and 19-year-olds who had received a benefit for at least six months would be paid the youth wage once they found work.
"I'm appalled that this Government thinks that because a youth has received a benefit they shouldn't qualify for the same rate as an adult. Are they a lower class of citizen?" Mr Greening said. "As youth workers, we encourage youth to be part of their community and become active, participating, equal citizens."
First Union, which represents about 12,000 workers in the retail sector, called the bill shameful.
"It's utterly appalling and is really yet another attack on workers," retail secretary Maxine Gay said.