Morris has missed City's last five matches due to the problem he picked up at Fleetwood Town last month but he hoped to join in with training this week.
He reported on Monday that the issue still didn't feel completely right, however, and received a routine injection in the area the following day to try and settle things down again.
Parkinson said: "With Josh, he just felt a slight niggle at the start of the week but we're sure it won't set him back for too long.
"Sometimes with knee ligament injuries like his, you can feel the odd tweak when you are going through the last bits of your rehab work.
"Josh is a naturally fit lad though, and he is still heading in the right direction. It will be great to have him back when we can."
Reece Burke is expected back at the club's training ground this Thursday following his extended spell on international duty with England U20s.
The defender has been away with England since the start of last week, featuring twice for the Three Lions during the four-team Mercedes-Benz Elite Cup tournament between England, Turkey, Holland and hosts Germany.
Burke sat out England's opening 3-1 win over the Netherlands before playing full games against Turkey and Germany.
A 2-1 victory over Turkey gave Burke and his team-mates a chance of victory in the tournament but a 1-0 loss to Germany meant they had to settle for second place.