"It was a really difficult game for us and Marseille played really well, but all that mattered was winning and we kept at it, so compliments to us all," he told UEFA.com.
"We made too many mistakes getting the ball out of defence and needed to play it around a bit better. If we'd controlled our possession better then we wouldn't have suffered so much.
"Borussia Dortmund are going to give it everything against us, but we'll give it our all too, even if it's not going to be easy at their place."
Napoli are currently second in the group, level on nine points with Arsenal.