Villas-Boas sought to shoulder the blame after Chelsea lost 2-1 at Bayer Leverkusen on Wednesday - a result that puts their Champions League qualification in jeopardy - but Cech has exonerated his boss.
The defeat in Germany was the latest setback for the beleaguered Blues, who have now lost four of their last seven matches in all competitions. They have made their worst start to a season since the Roman Abramovich era began, leading to speculation that Villas-Boas could be dismissed just a few months after joining from Porto.
However, Cech insists that the only thing that needs to change is the club's attitude to defending. "The manager is not on the pitch, we are on the pitch and we are making mistakes," he said.
"He cannot do anything about individual mistakes while he is standing by the bench. So the players are to blame and we know it and we try to make things happen and change. It is not easy but we keep going.
"We have been talking recently about the same mistakes: concentration and little details when we don't go to clear the ball. I think we need to be much more aggressive in terms of defending.
"There are no excuses. We need to look first at ourselves and then we can criticise the other people because we put ourselves in the situation where we were 1-0 up [against Leverkusen] and we could have killed the game off.
"Then there would be no discussion whatsoever about things that were happening in the game. We have to take it like that and make sure that this is the last time it happens."