Ole Gunnar Solskjaer felt referee Francois Letexier's relative inexperience cost Manchester United a penalty in their Champions League defeat to Young Boys.
The United manager also said that Mohamed Camara should have been sent off for his challenge on Cristiano Ronaldo at the start of the second half.
Solskjaer saw Ronaldo give United a 1-0 lead in Bern before Aaron Wan-Bissaka's sending off sparked a Young Boys comeback, sealed by Jordan Siebatcheu's stoppage-time winner.
Though Solskjaer believed that the evening would have taken a different turn had the 32-year-old Letexier punished Camara for bringing Ronaldo down while through on goal.
When asked whether he felt it was a red card offence, Solskjaer said: "Yeah, he shoves him with his arm, he's one-on-one and in front of him.
"But [Letexier] probably didn't do it because he had to send him off then so it would have been difficult. That's football sometimes, you get it with young refs."
On Ronaldo, who was replaced in the 72nd minute as Young Boys pressed for an equaliser, Solskjaer added: "You can never be surprised by the man.
"He scored another goal, he should have had a penalty and sending off the other way, he pounced on that mistake.
"He's exceptional but we have to look after him and it felt like the right moment to take him off."
Solskjaer did not have any complaints about Wan-Bissaka's red card, though insisted that there was no intent in the challenge on Christopher Martins.
"I can understand why [Letexier] gives it. Aaron takes a touch that goes too far, it's never a dangerous tackle because he hits him in the front of his foot.
"We saw sometimes with Harvey Elliot you sometimes can see bad injuries, it was never reckless or malicious.
"Maybe inexperience to go through without the ball but the boy wasn't going to be injured, and it makes it difficult after that with 10 men."
