Fresh from a shock 2-2 draw with Estonia, the Dutchman refuses to take the minnows lightly as they look to secure their qualification to the 2014 World Cup
Oranje slumped to a shock 2-2 draw with Estonia on Friday following Robin van Persie's last-gasp penalty, and Van Gaal has made it clear they should not expect an easy ride against a side who are without a goal in their World Cup qualifying group to date.
"That is not an easy game," he explained to reporters.
"Against such an opponent, it is always difficult. They will defend together and gamble on the counter.
"That makes it difficult for us. We have approached this game very seriously, just like every other.
"Of course we have much more quality, but that was also the case against Estonia and we did not win."
Van Gaal also jumped to the defence of centre-back Stefan de Vrij who received substantial criticism for his performance in Friday’s draw.
"The criticism came from the media, not the coach or my players. Stefan stood on the end of a chain of errors and football is a team sport," said Van Gaal.
Arjen Robben will miss the clash through suspension after picking up a yellow card against Estonia, and Van Gaal says he has made his feelings perfectly clear to the Bayern Munich man over his ill-discipline.
"That [booking] was not wise. I’ve also let him know. We don't have much depth on the wing," he added.
If Netherlands win on Tuesday and Romania fail to defeat Turkey, Van Gaal’s side will secure qualification to the finals in Brazil next summer.