"This should never happen on the Philippe Chatrier court," the 2009 French Open champion said. "I'm not happy about it. Obviously not one second I'm happy about it."
The normally calm Swiss says tournament director Gilbert Ysern quickly apologized. Ysern was also seen speaking to Federer's wife in the players' lounge.
The teenage-looking boy ran onto the clay court, put a hand on the 17-time Grand Slam champion's shoulder and tried to snap photos of them together with his mobile phone. This was as Federer was walking off court from his first-round victory over Alejandro Falla.
"It's true for all players that you have to feel safe when we play, feel safe on the courts," Federer said. "It shouldn't happen too often. It's happened twice in two days."
He said several kids also approached him Saturday during practice: "There was one who arrived and then followed by five kids. Nobody reacted in terms of safety, you know, security."
He spoke scathingly of security guards who took several seconds Sunday to react, with one of them eventually steering the boy away.
"You know, it's not just being there, standing there on the courts wearing a nice tie and suit. It's not that funny, you know," he said. "I hope that there is going to be a reaction from the tournament."