The Portuguese also declared “the people of Manchester will pull together as one,” after the devastating attacks on Monday night, which left 22 dead and 59 injured.
United players and staff trained on Tuesday morning, and held a minute’s silence at the club’s Carrington training ground for the victims.
They are to fly out to Sweden on Tuesday afternoon – ahead of Wednesday’s final against Dutch side Ajax – before walking the pitch at the Friends Arena in Stockholm tonight.
Mourinho and a player had been due to speak at 5.15pm tonight. That has been cancelled, but the Red Devils chief released the following statement ahead of the club’s departure from Manchester.
“We’re all very sad about the tragic events last night,” said the United boss. “We can’t take out of our minds and hearts the victims and their families.
“We have a job to do and will fly to Sweden to do that job. It’s a pity we cannot fly with the happiness we always have before a big game.
“I know, even during my short time here, that the people of Manchester will pull together as one.”
Executive vice chairman Ed Woodward called the attack “a senseless act” in an email to club staff, announcing that an event planned for after the Europa League final – for players and staff – would be cancelled “as a sign of respect for the victims and their families”.
Marouane Fellaini and Chris Smalling are set to be fit for the final against Ajax, having both trained.
The duo missed Sunday’s win over Crystal Palace after picking up knocks; Fellaini had been carrying a hamstring injury while central defender Smalling had a toe problem.