Gonzalez, 31, went 11-11 with a 4.57 ERA with the Nationals in 2016.
The club also holds a $12 million option on Gonzalez for the 2018 campaign.
Gonzalez hasn't won more than 11 games in any of the past four seasons after winning 52 over the previous three -- including a National League-best 21 in 2012 in his first campaign with Washington.
Gonzalez, who sports a 102-77 career mark, began his career with the Oakland Athletics in 2008.
Washington also announced it declined to pick up the option on right-handed reliever Yusmeiro Petit, who went 3-5 with a 4.50 ERA last season.