Moore reached an agreement to join the Cowboys on Tuesday night but changed his mind overnight and decided to retire from the sport on Wednesday.
The 33-year-old cited family reasons behind his sudden U-turn, claiming that he thought it was too late to uproot his family.
"I was wrestling with it all day, going back and forth with my wife and family. Finally, we decided, 'Let's go ahead and do it.' I didn't sleep at all. I was wrestling with it," Moore told ESPN.
"I realized it was too late in the game to uproot my family. I called my agent and said, 'I can't do it,'. I played the game for 10 years. I lived in a house. I didn't have to go from team to team, so this would've been a big transition for me.
"You really don't grasp it until you actually agree to something. Then it was like, 'Wow, I have to leave tomorrow for California'."
Moore is thought to have turned down a contract worth up to $2m in 2013 alone in favour of retirement.