"I think the result should be much better, and we can only blame ourselves and we didn't play in attack with that instinct," Mourinho told British media. "We stopped our counter attacks because of sloppy decisions, sloppy touches on the ball.
"Luckily our defenders were very much in the game. If I was a Man United defender I would be very upset with the attacking players, because they had to kill the game and they didn't."
United's inability to kill teams off has been a factor throughout the season. They sit fifth in the Premier League, with 12 draws in 30 league games.
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Leaders Chelsea have drawn just three.
"It's not just about the chances we missed, because we didn't miss many," Mourinho added.
"It's about the half chances, because the space is there, the time is there, but the end decision is not ... but this is what happened to us all season, we have chances but don't score goals."
United host Chelsea on Sunday before Anderlecht visit Old Trafford for the second leg of the Europa League quarter-final on April 20.
(Reporting by Aditi Prakash in Bengaluru; Editing by Peter Rutherford)
