The president, along with First Lady Melania Trump and several lawmakers, appeared live on the screen as part of a video package thanking U.S. troops for their service.
The hometown crowd cheered fans and soldiers displayed earlier on the screen, but there were boos and isolated "Lock him up" champs when Trump appeared, according to a Reuters reporter in attendance and videos posted on Twitter.
Reaction at Nats Park as President @realDonaldTrump is introduced pic.twitter.com/kO6EydX4lo
— Alex Moe (@AlexNBCNews) October 28, 2019
The frosty reception came on a day when Trump had announced the death of Abu Bakr al-Baghdadi, the leader of the Islamic State group, in a raid by U.S. special forces in northwest Syria.
Trump won just 4 percent of the vote in the District of Columbia in the 2016 presidential election. The U.S. capital is hosting its first World Series since 1933.
Trump did not throw out the ceremonial first pitch at the game, as many previous presidents have done. That task fell instead to celebrity chef Jose Andres, who founded a non-profit group to feed disaster victims around the world.
Andres also canceled plans to run a restaurant in Trump's Washington hotel because of Trump's disparaging comments about Mexicans, which led to a legal settlement.