Deion Sanders -- Pilar's Trying to EXTORT Me

Deion Sanders is firing back at his estranged wife Pilar, claiming her recent accusations -- that he's a narcissistic serial cheater -- are just a "shady" attempt to extort more money from the NFL star.

Deion's attorney, Jody Johnson, tells TMZ -- "The actions of Ms. Sanders and her attorney are nothing more than an attempt to avoid a legally binding contract that she no longer likes, by falsely assassinating the character of Mr. Sanders in an effort to extort additional money from Mr. Sanders."

The contract she's referring to ... the couple's prenup -- which Pilar wants the judge to toss out ... so she can make a grab for the lion's share of Deion's estate.

Pilar claims she was forced to sign the prenup under duress, but Deion says that's BS -- according to his lawyer, "Mr. Sanders committed to a generous financial agreement with his wife when they both voluntarily signed a premarital agreement."

Deion claims it didn't end there either, he also showered her with money and gifts before and during their marriage.

As for Pilar's attacks on Deion's parenting skills -- his lawyer claims, "Anyone who knows Mr. Sanders and observes him on a daily basis knows that he is a committed, ever-present father."

The lawyer adds, "Mr. Sanders will not be intimidated by these shady tactics and remains committed to resolve this matter in a court of law as quickly and amicably as possible."