According to Ciaran Kelly of the Manchester Evening News, at a promotional event in his native Sweden, the Red Devils striker said:
"The knee is almost there. I want everybody to have patience. And when I come back, the world will know."
Ibrahimovic tore his anterior cruciate ligament in April, and after initially leaving United on the expiration of his deal, he rejoined the club later in the summer on another one-year contract.
He has also taken to Twitter to show off his recovery:
The striker did not put a timeframe on his return to fitness, though his agent, Mino Raiola, told Francesco Fontana of La Gazzetta dello Sport (h/t Kelly): "Ibrahimovic? He is doing well, he could return in January but that is uncertain."
Red Devils boss Jose Mourinho is evidently at least optimistic Ibrahimovic might be back before then, having named him in United's UEFA Champions League squad.
The Swede will be 36 in October, and such a serious injury so late in his career could have brought it to a premature end, so it's encouraging to see him on the path to recovery.
Football writer Liam Canning was delighted with United's decision to offer him a new deal at the club:
While he did miss a number of chances and arguably slowed the team's play in the final third, he nevertheless contributed 28 goals and 10 assists in all competitions.
It will be fascinating to see what kind of role he will play upon his return now that United have Romelu Lukaku in place, and it seems he's on the right track to return in the relatively near future.