Ferguson's continued presence at matches last season was considered to be a hindrance to former boss David Moyes, who lost his job in April.
However, Van Gaal is confident that he will be able to get on with the Scot when he arrives at Old Trafford after the World Cup.
"I don't think [Ferguson] is the biggest problem," the Dutchman is quoted as saying by Goal.com. "I put more pressure on myself than others do.
"I'll undoubtedly have a drink with Ferguson. We've done that before and we like each other, but nobody can put more pressure on myself than I do, so I do not expect any problem with Ferguson."
Van Gaal, whose previous clubs include Ajax, Barcelona and Bayern Munich, signed a three-year contract with United on Monday.