The Premier League side has been linked with a move for the Dutch defender, recruited by the Scottish team two years ago for £2.6m from Groningen.
It has been claimed Southampton are preparing to offer almost three times what Celtic paid for van Dijk to take him to St Mary’s.
Deila has reacted to that by insisting the 23-year-old is an integral part of his team who he wants to retain as the Parkhead outfit bids to reach the Champions League group phase.
The Norwegian, speaking ahead of Wednesday’s qualifying fixture with Azerbaijani side Qarabag, said: “It is the same things I say all the time.
“We don’t need to sell him, we want to have him here and it is a day before a very important game. Virgil is very focused, happy and really wants to play Champions League with Celtic.
“Seven million? You think we would say yes to that? They haven’t bid. He is a top international player and everyone knows that.
“We want to reach the Champions League. We want to make this big club be successful, we need the best players and he is one of them.”