However, Mourinho has intimated that the recent success may have not been achievable without the Argentina forward.
"In 10 years' time, without Lionel Messi, the map of European football is going to change," he told talkSPORT.
"What Barcelona have won in the last few years was with Frank Rijkaard, Pep Guardiola and Luis Enrique as coach, but it's always with Messi."
Last week, Barcelona economic vice-president Javier Faus said the club could be forced to sell Messi, Luis Suarez or Neymar if the likes of Chelsea or Paris Saint-Germain tempted them with better salaries.
Mourinho also tore into the Spanish top-flight, insisting Barca and Real Madrid would not dominate English football in the same way.
The former Los Blancos boss said that there were only "four or five" meaningful games every season.
"I was in Spain but I didn’t enjoy it," he added to talkSPORT.
"I didn’t enjoy it because I won a title with a record in Spain with 100 points and 121 goals, but we played only three or four matches all season.
"I lost a title with 92 points, but again we played only four or five matches in the season.
"You feel the pressure that you have to win every match because if you don’t you are not champions. You have to win and win. But it is a big, big gap between the giants and the others.
"In matches in other countries you can win games when you are resting. In Spain and in Italy I won lots of matches resting, where you think ‘what next’, where you think which European game is coming, where you can rest players.
"This season I rested some players against Bradford City and I lost. That is English football. You are winning 2-0 and if you concede a goal you know you are going to have hell for the last few minutes and you might draw 2-2 and lose two points.
"This is the reality of the Premier League. You have no time. It’s not just about the number of matches, it’s the intensity. And it’s not just physical intensity, you feel the intensity mentally.
"I think the difference between the Premier League and La Liga is huge. Would they [Barcelona or Real Madrid] win the Premier League? Maybe yes. Maybe not."