The Czech Republic international has backed his opposite number to adapt to life in the Premier League ahead of the two sides' meeting at Stamford Bridge on Sunday
The Spaniard is set to regain his spot in goal due to an injury to Anders Lindegaard, who has been preferred by Sir Alex Ferguson in recent weeks, which will see him miss four to six weeks.
De Gea has come under criticism since his big-money move from Atletico Madrid last summer but Cech says he can sympathise with his opposite number and has backed him to adjust to the English game.
"You could see with De Gea at the start there was a challenge in the air which normally would have been given in Spain as a foul and was not given here and you could see the surprise," he told Chelsea TV.
"You could see every time it happened, he was surprised.
"This is where you sympathise with the guy because you know you have to learn quickly to adapt.
"I think he's doing well in terms of improving and understanding the game, but it takes time to adapt."
Cech's Chelsea team-mate Fernando Torres, who also moved to England from Atletico, echoed the keeper's thoughts that referees give more protection to players in Spain.
He said: "In Spain, the keepers are very protected from the referees.
"It's a massive difference in England, when the strikers or defenders can block the keeper and it's just 'Play on'.
"I am sure he's trying to improve that part, but it's not easy."