Amini's agent Buddy Farah recently stated that the Mariners had asked Dortmund for too much for the teenage midfielder but Central Coast chief Peter Turnbull has returned fire saying it was an offer which they would have lost out on.
"There was an offer there and we rejected that, it was an insulting offer," Turnbull told the Central Coast Express Advocate. "We then put a reasonable proposal to them and they rejected it.
"What people need to take into account is that Mustafa now takes extra special significance at the Mariners now that (Patricio) Perez is no longer at the club.
"It will take a special offer for us to let him go. We're not greedy, we are trying to do the best for the team and our supporters.
"We've never been a club to undertake contract negotiations through the media and that will never change. Some of the numbers quoted in the media have not been correct, we'll leave it at that. Our offer was fair."