Netherlands captain Mark van Bommel said in an interview published on Friday that the team heard racist chanting during a public training session in the southern Polish city of Krakow.
"We all heard the monkey chants," van Bommel was quoted as saying by De Telegraaf newspaper, "We can't accept that. We reacted well (coach Bert van Marwijk took his team to the other side of the pitch) and the situation was sorted."
The AC Milan midfielder added: "During the tournament, if any one of us is confronted with such a thing, we'll immediately go to the referee to ask him to intervene."
A senior UEFA official had told AFP on Thursday that a small group of protesters had targeted the Dutch team's training ground in Krakow on Wednesday but denied the demonstrations were racist.
De Telegraaf previously reported that a handful of the 25,000 fans who turned up to watch the Oranje train had made monkey noises at the side's black players during the warm-up.
But UEFA, which has a zero tolerance policy on racism at football grounds, said it had spoken to the Dutch squad and they said they had not seen or heard anything of a racist nature, the official said.
Instead, the official said that some Polish supporters were unhappy at European football's governing body for not making Krakow one of the four Polish host cities for the tournament and made themselves heard.
One journalist from Dutch radio RNW, however, maintained that some of the short-lived protest that was cut short by stadium officials was racist.
Photos showed some fans with banners with a red line through the Euro 2012 logo.
Van Marwijk, father-in-law of van Bommel, had said after the training session: "I congratulate the spectators who created an extraordinary atmosphere in the stadium."
The Netherlands play their opening match in Group B against Denmark in the Ukrainian city of Kharkiv on Saturday.