Mexico's Perez, now with Force India, has registered one podium finish this year in Formula One to sit 11th in the drivers' standings behind his replacement at McLaren - Kevin Magnussen (ninth) - and former team-mate Jenson Button (eighth).
Ramirez, who worked for McLaren from 1983 to 2001, believes compatriot Perez is not a team player.
"As a driver Sergio was actually not bad and I thought he was also getting better but McLaren wanted a new Lewis Hamilton, they wanted a driver who is faster than Jenson Button," the 72-year-old Mexican told German website motorline.cc.
"Sergio was not good enough as a person. He did not really cooperate with the team, he was at no time a part of the team, he was cocky. 'I am now a Formula 1 driver' - we know the drill.
"His attitude was very bad. He was unpopular with the engineers, with everyone in the team - he was regarded as very arrogant.
"And [McLaren CEO] Ron Dennis requires that his drivers are part of the team. From early in the morning until late at night you must always think of McLaren."
Ramirez added that individuals at Perez's other former team Sauber are also unimpressed by the 24-year-old.
"Unfortunately. I often criticise him in the media - but I do not criticise him as a driver, he's a good driver, but it does not integrate into the team," Ramirez said.
"It's such a shame - I was this year in testing at Jerez, there have spent some time at McLaren and Sauber, and neither team was able to say something good about Sergio. This is incredible - they all say that Sergio needs to change his attitude if he wants to stay in Formula One."
Ramirez also took aim at Mexico's other representative on the F1 grid - Esteban Gutierrez - claiming the Sauber driver does not have the "killer instinct" required to be winner.
"He's not a bad driver but he lacks this very small last step, there is a lack of killer instinct," Ramirez said.
"The Hamiltons and [Fernando] Alonsos have this killer instinct."