Tunisia were eliminated after losing 5-1 to Sweden and 4-0 to Japan in their opening two games. They changed their coach between those matches, with Herve Renard rushed in to replace the sacked Sabri Lamouchi following their opener.
The Dutch, who thrashed Sweden 5-1 after a 2-2 draw with Japan, are battling to top the group.
"We know that they changed the coach after the first match. But for everyone, it's an honour to play in the World Cup. So what I expect is that they will play full," Dumfries told reporters ahead of Thursday's match in Kansas City.
"Every game in the World Cup is a tough game. Everyone plays with honour, proud to represent their country. I expect that they will come with full energy, and we have to show it as well," the Inter Milan player added.
His remarks echoed Renard's after the match against Japan, when the French coach said Tunisia had to remain focused.
"Even if we are eliminated we still have a third game to play. We are in a World Cup," Renard stressed.
Dumfries also said the Netherlands took confidence from their emphatic win over Sweden, underlining their attacking depth. The 30-year-old provided two assists in the match, setting up goals for Brian Brobbey and Cody Gakpo.
"We know we have a squad with a lot of quality in front, a lot of players with the capability of scoring," Dumfries said. "It's a good sign and it gives confidence."