The Dutchman added that he was also enduring the worst injury crisis he could remember in his 23 years as a coach.
Van Gaal arrived at Old Trafford after the World Cup tasked with bringing the good times back to the red half of Manchester but his side have failed to deliver so far, taking five points from their opening five matches.
Despite investing heavily in attacking players during the recent transfer window, United's cause has not been helped by their defensive frailties, which were all too evident during last weekend's humiliating 5-3 defeat to promoted Leicester City.
"At this moment maybe (it is the hardest job) but you have to see in a year and not in one week that we have nine injuries and a red card," Van Gaal told a news conference.
"This club is in transition. We should have won last weekend and, if we had, we would be two points off second place.
"If we'd have won it would be different. You can't make one incident a regular one. We will overcome things. The season lasts more than one competition day."
Eighth-placed West Ham United travel to Old Trafford on Saturday hoping to take advantage of United's defensive worries as Phil Jones, Chris Smalling and Jonny Evans are all injured, while Tyler Blackett is suspended after being sent off against Leicester.
"I have to admit that I am never in this situation before so that is strange," Van Gaal said. "For me, it is difficult to understand because we are evaluating what we can do in a different way."
Van Gaal has experience of nurturing young talent having done so at Bayern Munich and the 63-year-old is ready to give United's academy players first-team opportunities.
"There are vacancies," Van Gaal said. "The younger players can have their chance. They are hungry to play the game.
"United's youth education has a level that can provide that. There's a big difference between youth games and the Premier League but in one game you can show yourself."