The 60-year-old Hall of Fame running back told ESPN that a friend affiliated with Texas A&M asked him to speak with Manziel. Campbell said he also has reached out to Texas A&M head coach Kevin Sumlin and the two of them exchanged messages last week.
"We gotta get him some help," Campbell told ESPN. "I know everybody says that, but if you've never been there, how can you listen to someone? I think some former Heisman winners like myself, some Hall of Famers that have done it all, he should sit down and listen to what we have to say because we've been through it all."
Manziel, a first-round draft pick by the Cleveland Browns, has struggled to stay out of trouble since entering the NFL in 2014.
In the latest off-the-field trouble, Manziel is being investigated on allegations of domestic violence against his former girlfriend in the early morning hours of Jan. 30.
Manziel's ex-girlfriend, Colleen Crowley, gave a statement to police and asked the district attorney to pursue charges. Her lawyer also told a Dallas TV station last week that Manziel punctured Crowley's eardrum when he struck her and that it will take a while to regain her hearing in that ear. Crowley also filed for a protective order against Manziel.
"I'm like everybody else that lives in Texas," Campbell told ESPN. "I'm disappointed, I'm upset a little bit. But I think at some point, you have to say everybody was that age at one time and we have to get back to what's important.
"I would tell him that I used to be 23 years old. At one point I had Texas in the palm of my hand as far as an athlete. At a very young age, my mother said it's not so important what you do now, it's what you do over your lifetime. Johnny's gonna be just like me eventually. He's going to sit down and have a chance to sit down and talk to people. Is he going to be remembered for (his problems) or is he going to be remembered for a guy that did like Von Miller? Got up off the carpet and did something about it."
Manziel's agent parted ways with the quarterback in the wake of the latest incident, and Manziel's family has been concerned for his well-being. His father, Paul Manziel, told the Dallas Morning News recently that his son won't "live to see his 24th birthday" if he doesn't get help.
Manziel likely will be waived by the Browns on March 9 when the new league year begins.
Manziel finished his second season with 1,500 passing yards, seven touchdowns and five interceptions in nine appearances (six starts) and a passer rating of 79.4. He rushed for 230 yards.