Wales international Cotterill has seen competition for places increase following the arrivals of Greg Stewart and more recently Kerim Frei.
The 29-year-old has made 29 appearances so far this season and found the back of the net three times.
His last appearance in a Blues shirt came as a late substitute during last weekend's defeat at Norwich City.
Bristol City, who are managed by Lee Johnson are currently struggling in 20th spot in the table, just three points above the drop zone.
The Robins are next in action this coming Saturday when they play host to Rotherham United.