Inzaghi is being linked with a move to the Premier League ahead of the end of the season.
But Marotta is confident of his commitment and told Rai Radio 1: "We are very happy with Inzaghi, I think the contract renewal is a formality, he has worked very well in recent years, he is a great point of reference for our corporate model from a technical point of view.
"He is one of the best coaches in the world around. He also has the advantage of having been an excellent player, we are very happy to have him with us. When the dust settles we will meet again and renew the contract."
Marotta was also asked about Inter's interest in Lazio winger Gustav Isaksen.
He replied: "We are the most prolific attack, if I remember correctly we only failed to score in one match. Inzaghi's game fits well with an offensively driven team.
"Isaksen? He is a good player, but every day the media attributes to us the interest of this or that player. We certainly have Lautaro-Thuram, the best attacking pair in Italy and a high profile at European level.
"We will make our program later with the sports director (Piero) Ausilio and (Dario) Baccin, we will take into account what the market offers and many evaluations, always with a view to building a competitive team for the objectives we have set ourselves."