In a speech on the sidelines of the Munich Security Conference Thursday, Juncker, who heads the European Union's executive arm, suggested some resistance to Trump's threat was in order.
"It has been the American message for many, many years. I am very much against letting ourselves be pushed into this," he said.
Juncker also said the EU's other spending commitments made up for any shortfalls in military funding.
"Modern politics cannot just be about raising defense spending," he said according to Reuters.
"If you look at what Europe is doing in defense, plus development aid, plus humanitarian aid, the comparison with the United States looks rather different," he said.
Juncker added that European nations should bundle their defense spending better and spend the money more efficiently.