United were held to a goalless draw at home to Southampton yesterday.
Lukaku was stretchered off and taken down the Old Trafford tunnel after an accidental collision with the Dutch defender.
Hoedt appeared to head into the back of Lukaku’s head.
The Belgian striker was left unconscious on the pitch and required medical treatment before he was further examined at the ground.
But Mourinho refused to pin the blame on Hoedt.
“He was just unlucky,” Mourinho told MUTV.
“I think the Dutch central defender goes with him for the ball and it’s unlucky for Romelu and unlucky for Hoedt.
“It was nothing aggressive and, hopefully, nothing important.
“But the first consequence of is he didn’t play for the rest of the game.”
Mourinho confirmed Lukaku is likely to be out for two matches.
He added: “I don’t know. I know that normally bad, bad news arrives immediately.
“Bad news didn’t arrive. I think that there’s a problem for the next two matches. For sure.”
Meanwhile, Chelsea thumped Stoke 5-0 earlier in the day to jump above United into second spot.