Rotherham recently failed with a £600,000 bid for the 21-year-old Australian international.
"He's not going, and I don't know if we would sell him," Cooper told BBC Sport. "I don't think there's any pressure.
"With all due respect to Rotherham, I don't think Mass would go there. It was a fantastic offer but I think he's worth more than that."
Luongo was part of Australia's squad at the World Cup in Brazil, though he failed to make an appearance for the Socceroos.