The 25-year-old arrived at United from Juventus in 2016 for a then-world record fee of £89 million (105 million euros).
But he was an unused substitute in Saturday’s FA Cup win over Brighton after being left out of the starting line-up for the Champions League loss to Sevilla.
“I don’t know why that is,” Deschamps told a press conference ahead of France’s friendly internationals with Colombia and Russia.
“I have not spoken to Paul yet, I’m sure I’ll hear more about it. But of course it’s a situation he won’t be enjoying.
“As to why or how things came to this, there may be many reasons.”
Deschamps played down any potential rift between the player and Mourinho.
“I have a great deal of talks with players at our training camps, to gauge their feelings. It’s not just Paul.”
Pogba has started just 24 matches for United this season, with manager Mourinho preferring Marouane Fellaini and youngster Scott McTominay in recent weeks.
Deschamps’ France, one of the favourites for the World Cup in Russia, face Colombia in Paris on Friday before travelling for a match in St Petersburg on March 27.
Barcelona winger Ousmane Dembele is back in the France squad after recent struggles with injury, having finally scored his first goal for the Catalan giants against Chelsea after signing last year from Borussia Dortmund for 105 million euros.
Deschamps said he has been encouraged by the 20-year-old’s form since his return to Enersto Valverde’s side.
“He has come back well, he’s been able to play several matches over the last three weeks and he’s better than he was a fortnight ago,” said Deschamps.
“He must still assert himself to be more decisive.”
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