Moreno explained that the riders were fighting for position heading into the final climb of the stage up Mount Etna when the incident occurred.
"My teammates and me were all in the line coming to the final climb, Team Sky came up on the left and Rosa wanted to get onto my teammate's wheel in front of me. When he realized I was resisting, he aggravated me to which I reacted by pushing him, unfortunately causing him to crash," Moreno said.
"I want to apologize for my reaction and make it clear that it was not my intention for him to crash. I apologize to him and Team Sky, as well as to my teammates and sponsors."
Bahrain-Merida condemned the action and supported the race jury's decision to eject Moreno from the Giro d'Italia. It means defending champion Vincenzo Nibali will be without one helper for the majority of the race, but general manager Brent Copeland said the action was unacceptable.
"This was unfortunate situation which happened during a tense moment of the race, however Javier's act is not acceptable," Copeland said. "On behalf of team Bahrain Merida we apologize to those involved."
Moreno is the second rider this season to be kicked out of a race because of a violent reaction to the inevitable fight for wheels: Andriy Grivko is currently serving a 45-day ban for punching Marcel Kittel in the face during the Dubai Tour.