The 26-year-old, who was loaned out to Benevento last term, was expected to join the Serie A side for the 2018/19 season.
The two clubs unexpectedly failed to agree terms, and Lazaar was told to report back to training.
Rafael Benitez was open to letting Lazaar leave, and the Moroccan could yet leave the club with the transfer window still open for Championship clubs (loan deals) and European teams until August 31.
Lazaar opens up
The full-back has spoken for the first time since his move failed to materialise.
He told Gazzetta dello Sport, as quoted by the Shields Gazzette: “On Friday morning, Newcastle had authorised me to fly to Italy. I just had to sign the contract.
“Several voices were coming, but, in the evening, the two clubs told me correctly that the deal had faded.
And now? I hope to regain my space. I will work hard to get back to the top and be the protagonist. If not, I will look around [for another club].
“Obviously, Italy and Serie A always remain in my heart. Try again with Genoa in January? Why not? I know [Genoa manager Davide] Ballardini well. He trained me at Palermo. I wish him a great season.”
Could he do a job for Newcastle?
Since joining the club in 2016, Lazaar has made just nine appearances for the Magpies.
Eight of those came when the club were still in the Championship.
Newcastle’s defence looks reasonably solid following the opening two Premier League games against Tottenham and Cardiff.
Paul Dummett has done OK at left-back, and at the very least Lazaar could play second fiddle to the Welshman.
The Magpies don’t really have any natural replacements to call upon should Dummett pick up an injury.
Benitez appears to be relaxed over Lazaar’s future, and could take or leave his potential sale.
The most important thing is for Lazaar to improve and get ready in case he is called to make his Premier League debut this term.