Toffees stars Rodwell and Pienaar are amongst the big names linked with summer moves away from Goodison Park.
But Dutch international Heitinga insists that the club need to keep hold of their star players.
"It is important for us and the club, and everyone who loves Everton - if everyone is fit then we have a really good team," he told Sky Sports News.
"Jack is a good player and I hope he stays, I also think it would be good for him and his future at a club like Everton.
"He gets his chance to play and gets minutes and it is good to have him in the squad."
On Pienaar he added: "Steven is an important player for us, I knew him at Ajax but he is better now and if we can keep the squad together we can have a good, beautiful season."