Talks have been going on between the Lazio defender and the Naples outfit but have yet to come to fruition.
"We're in a phase where we are quite far away, almost close to extinction," Ulisse Savini told Radio CRC on Monday. "We've agreed terms, but it seems that Napoli don't have the certainty required to complete the transfer.
"We are at Napoli's disposal, but I am obliged to look around as that is my job. Napoli have told me that they are waiting for certain situations at the club to be resolved, but if a player is good then it doesn't matter who is the coach of the team.
"I understand that Walter Mazzarri wants my client so we are rooting for Mazzarri to stay. We won't close the Napoli door, though, not until we have an agreement with someone else. What we haven't been able to do with Napoli for two months could still be done in a day."
Diakite's current contract with Lazio runs out at the end of the season.