McGregor is set for a lengthy spell on the sidelines after breaking his leg against Poirier at UFC 264 last month.
He has since undergone surgery and based himself in Los Angeles as he begins rehab.
UFC president Dana White expects the 'Notorious' to return to the Octagon in a year, with Aldo voicing his support for the Irishman.
That's despite the Brazilian sharing an epic rivalry with McGregor which culminated in his 13-second championship defeat at UFC 194 six years ago.
Speaking to Ag. Fight, he said: "First of all, I'm upset with the injury.
"It's quite hard, we work with our body, we try to keep it healthy because that way we can always be working.
"I think he can [get back to fighting at a high level]. I never doubt the champions, the mind and willpower of the champions. He has dominating before and was the lightweight and featherweight champion. It's all up to him. If he wants to come back at a high level, he can do it."
Let nothing stop you! @McGregorFast @tidlsport pic.twitter.com/hgdocp3F9q
- Conor McGregor (@TheNotoriousMMA) August 4, 2021
On McGregor's trilogy bout with Poirier, he added: "The fight was going well especially because Conor forgot [his promotional] side and tried to be the fighter and win until that leg situation happened.
"But, man, I think it's up to him [to return]. If he wants to come back again, he will work hard, abdicate from certain things to get there, dedicate himself and go back to the winning path."
McGregor has vowed to come back from his latest setback.
The 33-year-old has lost three of his last four UFC fights, with his lone victory coming against Donald Cerrone in January 2020.
As for Aldo, he faces Pedro Munhoz in the co-main event of UFC 265 this weekend.
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