The pair have been constantly linked with moves away from the Amsterdam giants over the past couple of seasons with both being regarded as being amongst the hottest properties in European football right now.
Barcelona had two bid turned down for De Jong in the summer, while sporting director Marc Overmars said De Ligt would not be allowed to leave the club in January.
Reports claim that Ernesto Valverde's men could have to pay up to 130 million Euros to sign the pair as they target a new midfielder and centre back in January.
And Cillessen, who plays with the pair at international level, claims both of them would like to join Barcelona.
"Everybody in the national team would like to play for Barcelona because it's one of the best teams in the world," he told SPORT.
On De Ligt, he added: "I spoke with him about it. He has the level, but he's still 19 years old. He's physical, strong, mentally strong, especially if you see the [Nations League win] against Germany. In the first half he didn't go so well, but he recovered in the second half. He was also excellent against Bayern Munich in the Champions League for Ajax."
And on De Jong, Cillssen compared him to one of his club team mates.
"He can play various roles," he said. "With the national team, he plays more like Busquets. But Busquets is on another level at the moment. I think he's undervalued by most people."