Cavani was their top scorer last season and won the Serie A Capocannoniere title.
"We must only thank Cavani for all he did at Napoli, giving so much for this jersey," said Pandev at a Press conference.
"Now it's up to us to do our best and score more goals. My natural role is second striker, while we have some very strong new signings and hope even more champions will arrive.
"We are trying out new things with Benitez and must only follow his instructions. There are a lot of expectations around us and we should win a trophy, as over the past few years we've only won a Coppa Italia."