West Ham have released a statement saying Arnautovic was not available for transfer.
They wrote on their Twitter account: "Marko Arnautovic has a contract and we fully expect him to honour it. He is not for sale."
West Ham boss Manuel Pellegrini believes Marko Arnautovic is ready and focused to play against Arsenal on Saturday, despite rumours of a January transfer away from the London Stadium.
The forward has been linked with a big-money move to China but Pellegrini insisted that the Austria international is fully committed to the Hammers.
He said in a press conference: "They are rumours. We know Marko is a very good player so maybe a lot of clubs will want him to play for their team, but at the moment he is a West Ham player and we want to keep him.
"I think Marko and all the other players involved in rumours have their heads here and want to continue playing the way they are doing so far.
"I am sure his head will be in the game against Arsenal and it will not affect his performance."