From a contract at the end of June and his departure from the city now confirmed, De Bruyne is associated with a move to Italy and Napoli.
Add to the speculation at the weekend were reports that De Bruyne's wife was seen in the house hunt of Naples.
Manna, however, told Sky Italia on Sunday evening after their 2-2 draw with Genoa: “It is normal that we are always focused on the market, alert on every occasion.
“But talking about it now is absurd; it loses the work of the boys and the coach; I don't think it's good. We work, alert on what could happen. But talking about it doesn't help us.”