Heads of state signed a communique in which they "reaffirm our unwavering commitment to all aspects of the Defence Investment Pledge agreed at the 2014 Wales summit".
The US President repeatedly attacked Europe and Brussels over the "terrible way" the US had been treated by the European Union, particularly with trade agreements.
During a tense summit, the businessman announced his wish that all 29 member nations should increase spending to two per cent immediately, and eventually double that to four per cent of GDP.
Trump said there had been "tremendous progress" after his "firm" warnings during the tense two-day meeting in Brussels, during which he singled out Germany for special criticism. "It's very detailed", Macron said.
The second day of the defence pact meeting was disrupted and repeatedly rescheduled, as Trump's insistence on renegotiating his allies' defence budgets took precedence over issues such as Ukraine and Georgia's vulnerability to Russian Federation.
He said North Atlantic Treaty Organisation is "more co-ordinated" and there's a "better spirit for NATO" - surprising sentiments considering Trump has long made his disdain for the alliance well known, and had even threatened to pull the US out of the alliance over the spending dispute.
Al Jazeera's diplomatic editor, James Bays, reporting from the Belgian capital, however, said that based on interviews with sources, "nothing it seems, in the closed-door meeting, was resolved".
He insisted it had been a "very good" summit because of the frank and open discussion it had hosted.More news: Game of Thrones racks up 22 Emmy nominations
Mr Trump also said he sees his Russian counterpart Vladimir Putin as a "competitor", not an "enemy", days before they meet for a high-stakes summit. Allies would be increasing spending by $33 billion or more, he added.
Excerpts from Trump's bombshell interview were published Thursday just as the president was scheduled to dine with May at the palace.
"We consider Trump a negotiating partner", said Kremlin adviser Yuri Ushakov.
FILE - Russia's President Vladimir Putin talks to U.S. President Donald Trump during their bilateral meeting at the G20 summit in Hamburg, Germany, July 7, 2017.
It would be "impossible" for Trump to unilaterally pull out of NATO, Ben Hodges, a retired USA lieutenant general who led the NATO Allied Land Command, told The House. 4 per cent is what people should be spending.
"President Trump should cancel his meeting with Vladimir Putin until Russian Federation takes demonstrable and transparent steps to prove that they won't interfere in future elections", the New York Democrat said.
"We are ready to address practically all questions relating to bilateral relations and the global agenda", Ushakov said. "I don't believe in walking into the room with a world leader who's an enemy, who's a strategic threat, unless you have a specific game plan".