The Red Devils were eliminated in the group stage phase of the Champions League on Tuesday after suffering a 3-2 loss to RB Leipzig, which saw the Premier League side finish third behind Paris Saint-Germain and their Bundesliga opponents.
Ole Gunnar Solskjaer's men will now join fellow English sides Tottenham Hotspur and Arsenal in the Europa League last 32.
Spurs boss Mourinho, who won the tournament during his spell as United manager in the 2016/17 season, claims the Manchester giants are a 'top team' who don't belong in the Europa League.
"Manchester United become one of the top favourites to win the competition," the Portuguese tactician told reporters, per Goal. "The teams that drop from the Champions League are strong and normally don't belong to the level of the Europa League.
"United are one of the top teams. The group was very hard with Paris Saint-Germain and Leipzig. We knew it was not going to be easy for any of them."
