West Ham are also preparing a bid for the impressive Scotland international who was the top goalscorer in the Championship last season despite Leeds struggling.
Newcastle boss Alan Pardew is desperate to add attacking talent to his squad with Loic Remy back at QPR and Shola Ameobi having been released.
Papiss Cisse is also injured and could miss the start of the season – leaving Pardew with no first team striker.
Cellino’s ownership of Leeds has been far from straight forward but rejecting this bid is a signal of intent from the Italian who claims McCormack is happy to stay at Elland Road.
“Newcastle made an offer for McCormack and I said no,” he said.
“He is happy to stay here and that made me proud.”
Newcastle are set to test Cellino again with another bid of around £8million that could be enough to take the 27-year-old to the North East.