Castro revealed earlier this month that Liverpool were leading the chase for the highly-rated 21-year-old, although no deal has yet been agreed.
The Sevilla chief insists that he will not be selling Moreno for less than the value they have set on the player - and Moreno has a release clause of £24.5million.
"It's true that there is interest from a number of clubs, above all Liverpool, in him, but we haven't had proper conversations about selling him," Castro told ABC.
"We haven't reached an agreement, but talks haven't broken down. We'll wait and see what happens.
"If Liverpool are interested in the player and pay the right amount, he will be sold.
"Signing any player from this club has a price and we will decide that price.
"If Alberto Moreno has to stay at the club he will stay but if a club pays the amount we think is big enough for him to leave, he will leave. But there is no pressure."
Not seen enough of him to hazard a guess at his worth, but at £20m I'm expecting something special!!! Any clues La Liga lovers? Is this guy the next Roberto Carlos, Maldini or Julian Dicks? Downing at £20m, along with Robbie Keane at similar money still haunt me.- sideshowbob