The Hammers had a £5million offer rejected by an increasingly weary Albion hierarchy yesterday, prompting a fairly strong statement from chairman Jeremy Peace.
And Di Matteo told the Birmingham Mail: "We have said it many times, put statements out, and we'll put another one out now. He's not for sale.
"I'm not concerned about him though.
"We've made our position clear but you can't force other clubs to not make these offers.
"Graham is a cool boy and he should be content in a club where he's loved and settled."