Rotherham United manager Andy Scott has branded Crawley's reported £100,000 bid for Lewis Grabban "embarrassing".
The League Two leaders made the offer for the 15-goal striker last week and the Millers were quick to dismiss it out of hand.
Scott insists it would take big money for them to accept any offers.
"People will always be interested in goalscorers because they are valuable assets to clubs," he said. "Just because we are a League Two side and we signed him for nothing people think they can take the mick.
"It's embarrassing to speak to a club and them make an offer like that. Crawley are a League Two side, Lewis has 18 months on his contract and we are under no pressure to sell him.
"If he was to go in this transfer window, I'd be saying 'it was an unbelievable offer and we couldn't turn it down'. That's the only way he'll be sold."