Donovan is preparing for the friendly against Mexico under new USA boss Jurgen Klinsmann.
"My initial reaction was one of sadness and compassion for Bob [Bradley] because we had been with him for five years," the former Everton attacker told the Washington Post.
"When you are with a coach that long, whether you agree or disagree, you become close to a coach. That was a little difficult. Moving forward, I've been excited about this. A fresh outlook is always good. Something different is always good when you get into the rhythm of doing something over and over. It's sometimes a little difficult, but we're all excited about it and I was certainly happy about the choice they made."