The 26-year-old is facing a fight to hold onto his job after the Jets drafted Geno Smith in the second round of the 2013 draft.
He endured a tough practice session, overthrowing several receivers and throwing an interception, which led to boos from supporters watching in the stands.
"I think that's bullcrap," Cromartie told the New York Daily News.
"My thing is, if you're going to be a fan, be a fan. You don't come out here and boo anybody."
Rex Ryan's side missed the playoffs for the second consecutive season last year as they finished 6-10.