Frenchman Simon had chances to win both sets, but he was eventually beaten by the former world number one in two tiebreaks.
"Well, he was just more opportunistic," he told reporters. "We had a close match. I had a set point in the first, two in the second. It's just a few points deciding it, and he was always really good on these points. He played some great shots.
"He's putting a lot of pressure. He's always showing you that he is ready to be really aggressive on every shot. So he keeps you under pressure."
The title was the fourth that Federer has won in 2014.