Porto have told Chelsea they must meet Hulk's €100 million buyout clause if they want to sign the Brazil striker.
Porto's chairman Jorge Nuno Pinto da Costa has quashed rumours of a transfer.
He insists: "I've said it before, we would not sell Hulk and therefore Chelsea must activate his contract."
Hulk is under contract at the Portuguese champions until 2016, but his agent recently revealed a move to Chelsea would interest him.
"We know there is lots of interest from Europe, but the player has told me privately Chelsea is his preferred destination," he said.