In the lead-up to Napoli's clash with Sampdoria on Monday, Benitez spent a chunk of his press conference responding to questions about possible additions during the January transfer window, although the Spaniard said most players linked with his club do not interest him.
Napoli have been linked with Luiz, Mata, Barcelona's Javier Mascherano and Lyon's Maxime Gonalons, while reports have suggested Colombian striker Duvan Zapata may leave the club.
"I am pleased with the squad we have," Benitez said on Sunday.
"There has been talk of a departure for Duvan Zapata but that is not true. I am happy with him and he stays here.
"I read in the papers that we are close to a deal for Mascherano, David Luiz and Mata, but that is not true. It is very difficult to get players like that.
"On most of the players linked with Napoli, there isn't a real interest from us.
"Signing a defender? At Christmas I watched the Premier League and I didn't see any players at (Raul) Albiol's level. And there are few players in the market stronger than (Miguel) Britos and (Federico) Fernandez."
Benitez says Hamsik is not far away from returning to the first team, although the Slovak midfielder will miss the clash with Sampdoria, while the 53-year-old coach paid tribute to the Genoese club's new boss Sinisa Mihajlovic, who has overseen a six-game unbeaten run since taking over from Delio Rossi.
"Samp have a new coach with a lot of character," Benitez said.
"I just hope Mihajlovic stays on the bench, as he might want to step on to the field and take some free-kicks."
