The world number one had little difficulty seeing off Berdych in a match affected by rain at Roland Garros, emerging victorious 6-3 7-5 6-3.
However, Djokovic risked potential disqualification early in the third set when he tossed his racquet behind him, narrowly missing a line judge in the process.
Asked about the incident in his post-match media conference, Djokovic said: "I threw a racquet on the ground and it slipped and almost hit the line umpire. I was lucky there. That's all.
"I'm trying not worry about it at all. I am aware that I have been lucky, and I apologised to people that have been in this particular situation with me and that could have been hurt by my racquet.
"But it was never the intention. It was just some unfortunate bounce, but fortunate ending of that scenario. That's all I can say."
Djokovic will now face Dominic Thiem in the semi-finals after he came from behind to defeat David Goffin in four sets.
Of Thiem, who had previously not gone beyond the fourth round of a grand slam, Djokovic added: "He's one of the leaders of the new generation. I'm sure he's very motivated to show himself and others that he deserves to be at the top and compete for biggest titles.
"He's playing the best tennis of his life, no doubt about it. The results are showing that. He's been playing a lot this year, practically every week since February-March.
"You know, he's been keeping fit, as well, which is quite amazing for somebody that hasn't had that kind of scheduling before in his career.
"He's played a lot of matches, especially on clay, which is his favourite surface. Yeah, he plays with a lot of speed, with a lot of power.
"I'm sure he's going to give it all in semis. But I have something to fight for, as well. It's going to be a good one."