0349 GMT May 22, 2018
"Not going to the World Cup is difficult for those who, like us, have always been cheering for the national team," Mancini told a press conference at the national training center at Coverciano, near Florence, AFP reported.
"I feel the need to do something for the national team and think it's the right time for me. I want to build something for the years to come and bring Italy back to the top."
Italy has been without a permanent coach since Gian Piero Ventura was sacked after the four-time world champion failed to qualify for the World Cup for the first time since 1958.
Former Manchester City and Inter Milan coach Mancini signed a two-year deal on Monday after severing his lucrative contract with Russians Zenit Saint Petersburg.
The contract, reportedly worth €2 million ($2.3 million) a year, will see Mancini lead Italy's bid to qualify for Euro 2020. If successful, it will be automatically extended until June 2022, ahead of the World Cup in Qatar.
His first match in charge will be a friendly on May 28 against Saudi Arabia in Switzerland.
He also said he would talk to recently retired Italy great Andrea Pirlo about joining his coaching setup.
In Mancini, Italy has a coach with a solid track record as a title-winner, with 13 trophies in club football.
He led Manchester City to its first English league title in 44 years in 2012, and won three Serie A crowns with Inter. He also won the Italian Cup with Inter, Fiorentina and Lazio.
Since leaving England in 2013, Mancini coached Galatasaray, whom he lead to a Turkish Cup success, and returned to Inter before joining Zenit last June.
But this will be his first international coaching job.
"I don't know if this will be my most difficult challenge, if you coach a club and you don't win everyone is angry with you, here there are 50 million people.
"That's beautiful too, though, because if you win something important there's huge satisfaction. It's not an easy challenge, but nothing is easy."