Green-Beckham, who turns 21 this weekend, was involved in an incident last weekend at a Columbia apartment in which he allegedly forced his way into an apartment and pushed a woman down a short flight of stairs.
Police responded, but Green-Beckham was not arrested and is not facing charges because the victims decided not to press charges.
"This decision was made with the best interests of all involved in mind," Pinkel said in a statement issued by the Missouri athletic department. "Dorial's priority going forward needs to be focusing on getting the help he needs. As we have all along, we will continue to do everything we can to assist Dorial and his family.
"We care deeply about Dorial and his well-being, but hopefully he can benefit from a fresh start."
The No. 1 overall recruit in the class of 2012, Green-Beckham led the Tigers last season with 59 receptions for 883 receiving yards and 12 touchdowns, helping Missouri capture the SEC East title.
Green-Beckham released this statement earlier Friday:
"First and most importantly, I take responsibly for my conduct and my mistakes. Don't blame my girlfriend or her friends for anything. I am not looking for sympathy. I thank those who have given me concern. I have been young and dumb. I want to be better.
"During my suspension I'm entering counseling. With help, I know I can be stronger emotionally and spiritually. My relationship with God, my family, friends, teammates and coaches are most important in my life, not football. It may not be possible to fix everything, but it won’t be for not trying."
Green-Beckham was arrested in January on a charge of marijuana possession during a police traffic stop, but the charges were dismissed after another passenger in the vehicle in question took ownership of the marijuana.
As a freshman, Green-Beckham was suspended by Pinkel for one game after being one of five players arrested and charged with marijuana possession.