Smalling was heavily criticised for diving during the match, while Jones put in a mediocre display in a defeat that left the Red Devils just four points ahead of fifth-placed Tottenham Hotspur.
According to The Mirror, Mourinho has told the United hierarchy that they must start spending big on defenders in wake of Liverpool's £75m move for Virgil van Dijk and Manchester City's £57m outlay on Aymeric Laporte.
The report goes on to claim that France international centre-half Varane, who made his debut at Real Madrid when Mourinho was manager, is top of the Portuguese's shopping list.
United have also been linked with a £50m summer swoop for Leicester City and England defender Maguire, who has impressed after moving to the King Power Stadium from Hull City last summer.
Mourinho has been without centre-half Eric Bailly for the past three months as the Ivory Coast international recovers from ankle surgery.