Referring to the break-up, Timberlake told British GQ that, "It's hard for me to talk about because we're talking about the person that I love and respect and I would never … if I hear anyone say anything bad about Cameron then I'll have something to say to them."
Diaz and Timberlake issued a joint statement in January confirming they ended their romantic relationship. They said they mutually decided to split but still have "continued love and respect for one another."
Since their split, Timberlake has been linked to actresses Jessica Biel and Scarlett Johansson, who stars in one of his music videos.
The singer didn't say much about another ex in the news, Britney Spears. "Honestly, I am so far removed from that situation," he said. Ironically, there is a pic Timberlake shaving his head in the issue.
Photos: Timberlake Hosts Kids Choice
The singer also admits that he regrets teaming with McDonald's for an advertising campaign back in 2003.
"McDonald's market share went up by 25 percent when I changed their image. Hmmm, funny, isn't it?" he says.