Gattuso chose to step down after Italy lost their World Cup qualifying playoff to Bosnia on penalties last week.
Ventura experienced the same in 2017, when as Italy coach he oversaw their playoff defeat to Sweden to miss the 2018 World Cup in Russia.
Asked about advice for Gattuso, Ventura said on Rai Radio One: "It's clear he'll be disappointed right now. I've been there, too. You feel responsible for not achieving your goal. The important thing is that, deep down, he knows he's done his best.
"I advise him to calmly start over and redo the work he's always done. With the understanding that this with the national team was a bad setback, but it can happen in football."
Ventura also stated: "It's not all the coaches' fault, that's obvious. He has his responsibilities, but it's not a problem with the federal president or the coach, but with the culture, with the system. We always pretend nothing is happening."