The 21-year-old Spain international has been heavily linked with a move to Anfield in recent weeks after an impressive season that culminated in UEFA Europa League success.
With Brendan Rodgers looking to strengthen his defence in a bid to improve on their second-placed finish in the Premier League last term, Castro has confirmed Liverpool's interest in Moreno.
However, the Sevilla president warned that the club will not be rushed into selling their prized assets.
"It's true that there's interest from Liverpool and we're waiting to see if that turns into a reality, which right now, it isn't," Castro told the club's official website.
"What I'm clear about is that we'll not force anyone to stay at Sevilla.
"Whoever wants to leave can do so, but we'll be the ones setting the prices.
"This club is experiencing a time of economic stability and we don't need to sell.
"We're going to be firm about this and we'll only consider selling outside the market, which gives us the opportunity to make our team competitive."
Another of Sevilla's standout campaigners last term was Ivan Rakitic, with the Croatia international reportedly attracting interest from Real Madrid and Barcelona.
The 26-year-old is entering the final year of his current contract and Castro has expressed frustration that a new deal has not been signed yet.
"The contract renewal offer to Rakitic is really important to us, as a part of our budget for the next season. We want Rakitic to stay so that the team remains powerful, we really want him to stay," he added.
"Rakitic still has a year left on his contract and we'll have to analyse what comes. The truth of the matter is that many months have gone by, since we reached an agreement with him and he's still not signed.
"We're frustrated about that and I am particularly."
