The incident happened when the two riders were jostling for a wheel ahead of the final climb to Mount Etna.
“My teammates and I were all in the line coming to the final climb, team Sky came up on the left and [Diego] Rosa wanted to get onto my team-mates wheel in front of me," Moreno said.
"When he realized I was resisting, he aggravated me to which I reacted by pushing him, unfortunately causing him to crash.
"I want to apologise for my reaction and make it clear that it was not my intention for him to crash. I apologise to him and Team Sky, as well as to my teammates and sponsors."