Former Manchester United players Wayne Rooney, Paul Scholes and Nicky Butt questioned Sesko’s decision to miss the club’s 1-1 draw with Fulham before withdrawing from international duty.
Sesko has now missed the final three games of last season, United’s pre-season matches and two of their opening fixtures this campaign because of the injury.
Cesar believes the 23-year-old needs time rather than additional criticism.
“If you play for a club like this, it happens,” Cesar said.
“It’s not easy for Benjamin. He’s going through a tough period in his career, as he hasn’t had injury problems until now. This is an unusual injury that takes time to heal.”
The Slovenia coach also urged Sesko to surround himself with people he trusts while recovering.
“All of us around him need to stay positive because that’s what he needs. He needs time, and Slovenia needs him too when he’s healthy.”
Oblak, who has spent more than a decade playing under intense scrutiny at Atletico Madrid, said he understood the pressure Sesko is facing following his £74 million move to United.
“The whole situation is certainly not easy. He transferred to a big club very quickly. He’s under a lot of pressure,” Oblak said.
“I know that in such clubs the pressure is always enormous. Especially when injuries come, it’s very difficult.”
The Slovenia captain believes Sesko can respond when he returns to fitness.
“You just have to believe in yourself, aim to heal and come back as soon as possible, and to show everyone – those who think otherwise, who think you can’t do it – that they are wrong,” Oblak said.
“I believe that he will succeed. That he will stay strong. That his head will hold up. And that when he returns, he will be at the highest level again.”
Sesko has not played for Slovenia for more than a year and will miss the forthcoming Nations League fixtures while he continues his recovery.