The centre-half was handed a six-month ban earlier this year after testing positive for a banned substance, but that suspension has now been served.
The club are, however, to look into the matter further, with Toure said to be disappointed and shocked at the latest turn of events, and is planning to contest any further punishment imposed upon him.
He has been drafted back into Mancini's plans since serving his ban, unlike team-mate Carlos Tevez who continues to be a first-team outcast at the Etihad Stadium following an investigation into his behaviour during a Champions League clash with Bayern Munich.
Toure insists he has done nothing wrong, with the failed test blamed on a slimming tablet, but City are planning to press ahead with their hearing.
Mancini said: "I think Kolo is a different situation (to Tevez). It was a mistake -a totally different situation.
"In the other case I think that every player should have good behaviour, always."
Asked if Toure would face a disciplinary hearing, he added: "I think so, yes."
The timing of the hearing is said to be down to a delay in legal teams being able to set an appropriate date.