The Netherlands coach has revealed he was approached to take over at White Hart Lane following Andre Villas-Boas' dismissal in December.
But while the former Barcelona and Bayern Munich boss remains hopeful of managing in the Premier League, he felt it would have been wrong to manage Tottenham while leading his country.
Asked whether he had rejected the Spurs job, Van Gaal told Sky Sports News: "Everybody knows it so I can admit it. I don't do things in a double function (occupying two jobs at the same time).
"You have to give an example to your players that they have to focus on the national team and that is my ambition also."
After taking the Netherlands to this year's FIFA World Cup in Brazil, the 62-year-old Van Gaal indicated that his next move will either be to England or into retirement.
"I have refused (the Tottenham job) but maybe there will come another chance. That is the difficulty with coaching. When you are free, then maybe there are no vacancies," he added.
"When you are working, then there are vacancies. It is always difficult.
"After the World Cup I shall retire or, if there is a Premier League club, I shall think about it."
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