Inter Milan have reportedly agreed to sign midfielder Tonali on loan with an obligation to sign him next summer for £31.3million.
"I appreciated the professionalism of Paolo Maldini, who is very much in the style of the historic Milan approach," Cellino told Sky Sport Italia.
"I don't want to add anything more on that, as I do not wish to be inopportune or too free with my words…
"Beppe Marotta always confirmed the strong interest that Inter have for the player, so I tried to avoid negotiations with other clubs, including ones from abroad.
"However, this lad needs to know what his future holds. I am in no rush, but Tonali is."