LeSean McCoy is adamant ... he NEVER assaulted a woman on a party bus back in December -- and claims his accuser is just trying to shake him down for some cash.
TMZ spoke with McCoy's lawyer, Andrew M. Smith, who tells us, "The allegations against LeSean McCoy are completely, unequivocally false."
Smith continues, "There are no criminal charges pending [against McCoy] and no probable cause was ever found."
As we previously reported, a woman using the alias "Mary Roe" filed a lawsuit against the Philadelphia Eagles star ... claiming she was assaulted and badly injured on McCoy's party bus back in December after she objected to being sprayed with water.
Cops say ... when they interviewed the woman shortly after the incident, she had no visible injuries.
McCoy's lawyer says, "This is sadly an attempt to extract money and LeSean will vigorously defend any attempt to collect money through a personal injury claim."