"It's looking that way," Pettine said.
With Connor Shaw out after thumb surgery, the Browns will discuss adding another quarterback.
Pettine said Manziel has dealt with elbow soreness since high school, and been able to manage it. Because of this, Pettine sees this issue as "a minor setback."
"We just wanted to confirm there was nothing structural, and that is the case," Pettine said. "The MRI was certainly a positive result."
Pettine said if this were the regular season Manziel probably would be able to play. Because it isn't, the team will be cautious.
Manziel has not thrown with his right arm in practice since Sunday, when he left practice early. He did not throw Monday or Wednesday.
"It hasn't come back as quickly as we had hoped," Pettine said. "To be cautious, we didn't want to rush him back now for a preseason game and have it be something that is chronic."