Johnny Manziel acknowledged "rookie mistakes" when he met with the media on Friday, according to ESPN.com's Pat McManamon.
The 21-year-old has come under fire for his off-the-field antics this offseason.
"At the end of the day I've made some rookie mistakes," Manziel said. "There were some things I wish I could have gone back and done a little differently."
But he also defended his partying ways.
"I don't think there's anything wrong with me going out and having a nightlife and a social life," Manziel said. "I'm 21 years old and it was the offseason and it's free time for us."
It had been reported that the team was "alarmed" by the photo of Manziel rolling up a $20 bill in a Las Vegas bathroom.
"I've talked about that with [head] coach [Mike] Pettine, talked about it with [general manager] Ray Farmer and the people I need to talk about that with," Manziel said. "Moving forward they're good with everything and I've told them everything I need to and everything's been good."
Manziel, who Pettine said would start as the team's backup to Brian Hoyer, will see his first NFL action Saturday, Aug. 9, in Detroit.
- Chris Mascaro