The 21-year-old has been criticised in some parts for his off-the-field antics after being pictured in Las Vegas during the off-season.
However, Hawkins has defended the signal caller and has insisted that he has worked extremely hard during his side's organised team activities to get up to speed for life in the NFL.
"Johnny's all business, man," Hawkins told SiriusXM NFL Radio.
"I can't speak for all the other stuff because all I know is the Johnny I see in his playbook all day and trying to learn the plays and pick up an NFL offense, which is extremely hard for anybody, much less a guy who left college early.
"He worked his butt off, and I think that is all you can ask of him."
The Browns selected Manziel 22nd overall in the 2014 Draft.