Pogba left Turin for Old Trafford in a record-breaking transfer ahead of the 2016-17 campaign but has failed to live up to his price tag since returning to Manchester.
Barzagli acknowledges Pogba could not have foreseen Juventus' European success but believes their run to the last four could be tinged with regret for the France international.
"I saw Pogba the other day via video chat. He was happy that we reached the semi-finals of the Champions League and is cheering for us," Barzagli told Tuttosport.
"Whoever leaves this group will always be part of it. Our biggest strength over the past few years has always been the team.
"On the other hand he would surely have liked to be there.
"But they are decisions you make. Nobody can expect to leave and then see your team reach the final four of the Champions League next season."
Pogba, meanwhile, has already lifted the EFL Cup with United and is still in the race for Europa League glory.