United had originally taken the lead and looked relatively fluent and in touch with each other throughout the game compared to other away performances so far this season.
Ander Herrera‘s strike set United for just their fourth away win of the season but a quick equaliser from Ki, followed by Jonjo Shelvey’s deflected winner, saw United lose ground in the race for top four.
And van Gaal was left scratching his head after what he described as a good performance from his team, claiming Swansea didn’t deserve the win.
“No,” he responded when asked if Swansea were worthy winners.
“When you think that they deserved the game you have to write it, eh?
“This is always frustrating when you lose and are the dominating team, so I agree that you’re disappointment is much bigger because of that, so I agree.”
Whilst the likes of Robin van Persie, Marouane Fellaini and Angel Di Maria were poor on what turned out to be a frustrating afternoon, van Gaal accepted some players were ‘not effective’ but wouldn’t single out individuals.
“You have to see the slow motions of the match, then you can see which players were not effective,” he added.
“I think also a lot of the chances came because of the hurry, the pace of the action. And sometimes you can control the ball instead of shooting directly, but normally we are very effective so it’s amazing we have lost today.”
United now need to re-group ahead of a very winnable game against Sunderland at Old Trafford on Saturday.