Holland coach Van Gaal is in talks about the manager's job at United.
City's Spanish chief executive Soriano - who worked at one of Van Gaal's former clubs Barcelona - believes the 62-year-old is a confrontational coach who risks alienating players wherever he works.
Soriano said: "If you treat your people badly, they remember. One day you make an error and they kill you. I've seen this in many clubs.
"He is very tough, people don't like him, but he wins. And one day you don't win - and when you don't win, everybody that is angry with you will come back to you and try to kill you.
"In the movies this works, in real life it doesn't."
Soriano made his comments at a conference in March, before he knew about United's interest in Van Gaal.
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