Van Gaal says people in Barcelona always blame foreigners when things are bleak and has advised his compatriot not to pay much attention to the naysayers.
Barcelona have started the campaign poorly as they currently sit ninth and bottom on the La Liga and Champions League tables respectively.
The recent defeat at the hands of Benfica and Atletico Madrid has piled up the pressure on Koeman and many fans have called on the board to sack the Dutchman.
Club legend Xavi Hernandez and Antonio Conte are among the names tipped to replace the former Everton man in case he is shown the exit door at Camp Nou.
Van Gaal was speaking to the media ahead of Netherlands home game against Gibraltar in the World Cup qualifiers on Monday and the former Barcelona head coach defended Koeman by insisting the current state of the club is historical.
"History is repeating itself," he said. "These are typical things that happen at Barcelona.
"When things go well and you make important contributions, like Frenkie de Jong has done these past couple of years, then there's nothing to worry about.
"But, when things go badly, people at Barcelona always look at the foreigners. In this case, that's the coach. "I'd advise him to not pay much attention to it all."
