The Premier League outfit have been strongly linked with a move for the midfielder in recent months, but Bernard believes that a deal is unlikely.
"For the money that's been spoken about [for Grenier], it's never going to happen," Bernard told the Evening Chronicle.
"I think if he goes, it'll be for £20m. It could even be a Champions League team. For me it will be a surprise if he goes to Newcastle. Sadly it could be a 90% no for Grenier to Newcastle."
Newcastle finished 10th in the Premier League last season.