The French international joined the Gunners from Montpellier during the summer for a fee in the region of £12m.
Having now experienced a number of matches in England, the 26-year-old feels that he is coming to terms with a new style of football.
"I have to be prepared to battle against some very tough and physical defenders who go for it," he said. "That's the fighting spirit you find in England. The Premier League is the best in the world and it has more intensity than the French League.
"You need to be ready physically and there are a lot more better players, like in La Liga."
Giroud netted his first Premier League goal during Arsenal's 3-1 victory over West Ham United before the international break.