The Manchester United winger was shown a red card after clashing with Raheem Sterling 11 minutes from the end of the match which ended 2-2.
Valencia grabbed the Liverpool player by the neck in retaliation to a bad tackle by the 19-year-old forward who went over the top of the ball.
He said: "I apologised to the team after the match and the coach.
"I am sorry for the fight with Sterling. When he tackled me I thought about Segundo Castillo.
"He nearly missed the World Cup because of injury and I feared I would too but thankfully I am OK."
Team-mate Castillo nearly missed out on Ecuador's World Cup squad because of a knee injury sustained against Mexico.