Adams' lawyer denied the claims to the Times.
Responding to the report on Twitter, Adams said: "I am not a perfect man and I have made many mistakes. To anyone I have ever hurt, however unintentionally, I apologize deeply and unreservedly.
"But the picture that this article paints is upsettingly inaccurate. Some of its details are misrepresented; some are exaggerated; some are outright false. I would never have inappropriate interactions with someone I thought was underage. Period.
"As someone who has always tried to spread joy through my music and my life, hearing that some people believe I caused them pain saddens me greatly. I am resolved to work to be the best man I can be. And I wish everyone compassion, understanding and healing."
Adams released his debut album in 2000and has earned seven Grammy nominations. He famously covered Taylor Swift's Grammy-winning "1989" album in 2015, a year after its release. He has also worked as a producer behind the scenes for acts like Willie Nelson and Jenny Lewis.
Last month Adams performed at a tribute concert for the late rock singer Chris Cornell.
Ava said Adams constantly questioned her about her age throughout the nine months they exchanged text messages. The report said she never showed him any identification, and he had pet names for her body parts.
"If people knew they would say I was like R Kelley lol," he wrote to her via text in November 2014, when he was 40 and she was 16. R. Kelly has been accused of sexual misconduct with women and girls but has denied the allegations.
"Mr. Adams unequivocally denies that he ever engaged in inappropriate online sexual communications with someone he knew was underage," Andrew B. Brettler, Adam's layer, told the Times.
The singers Phoebe Bridgers and Courtney Jaye said Adams behaved inappropriately during their relationships.
In an interview with The Telegraph last year, Bridgers said recounted when she met Adams in 2015. "A mutual friend in LA was like, 'Ryan would like you'. He really was just trying to get me recording and trying to get Ryan to hear me, but Ryan was like, 'Let me see a picture of her'."
Bridgers says that she and Adams "ended up hanging out all night and recording a song together called Killer. Then, a couple of weeks later, he was suddenly trying to hook up with me. I was super-down and had just broken up with my high-school boyfriend. We slept together on his 40th birthday and I'd just turned 20."
Moore, one of the stars of NBC's award-winning "This Is Us," burst on the scene as a teen singer and had musical success in the late '90s and early 2000s. She claimed Adams stalled her music career and told her, "'You're not a real musician, because you don't play an instrument.'"
"His controlling behaviour essentially did block my ability to make new connections in the industry during a very pivotal and potentially lucrative time - my entire mid-to-late 20s," 34-year-old Moore said to the Times.
