NY Giants Co-Owner -- 'I Feel Badly For Manziel' ... His Life's In Danger

NY Giants co-owner Steve Tisch says it's time for Johnny Manziel to stop worrying about his career -- and start worrying about his life ... telling TMZ Sports, "He's got an issue that he really finally has to acknowledge."

Tisch was leaving Il Pastaio in Beverly Hills when we asked how Manziel's appearance at Coachella with Josh Gordon was going over in NFL circles.

Tisch basically told us what everyone was already thinking -- it's a bad move. But there's a deeper issue.

"I feel badly for Manziel," Tisch said ... "but I think he's got an issue that he really finally has to acknowledge. Not to save his career, but to save his life."

For his part, Manziel refuses to go to rehab -- insisting he does not have a problem.