That’s according to ESPN FC pundit Alejandro Moreno.
The Spaniard has been heavily linked with a Bernabeu exit, with United set to go toe-to-toe with fierce rivals Manchester City for his signature.
Isco’s future at Real may be in doubt, with club president Florentino Perez ready to oversee a major squad makeover this summer.
The 25-year-old has featured regularly under Zinedine Zidane this season but the Frenchman’s future at the club is in doubt following a miserable campaign in La Liga.
Manchester City – 11/2
“There’s nothing about Manchester United that’s creative.”
ESPN FC pundit Alejandro Moreno
And despite United’s interest, Moreno believes Isco will be put off by Mourinho’s negative style of football.
“No (he shouldn’t go to Man Utd),” Moreno said.
“The reason is because if you look at the creative players that have gone to Manchester United and are playing under Jose Mourinho, they’re stifled, they’re suffocating.
“There’s nothing about Manchester United that’s creative.
“I don’t think you want any part of that if you’re Isco, not under Jose Mourinho.”
United are currently second in the Premier League, only two points clear of Liverpool.
Mourinho’s side return to action next Monday as they visit struggling Crystal Palace (8pm).