Robin van Persie scored twice, as did Danny Welbeck toensure David Moyes' reign as United boss started with a victory.
With the score at 3-1, Bony netted a consolation for Swansea but the contest itself was already over.
"Our plan was to put Manchester United under pressure," Laudrup said.
"It succeeded quite well until the 33rd minute. Van Persie didn't touch so many things and suddenly you saw the difference.
"To concede two in two minutes against Manchester United is too much. Once he got the third we knew it was game over.
"They got a lot of confidence. Once a team like Manchester United gets more confidence they can play the ball around like that."