May added that the Improvised Explosive Device was "intended to cause significant harm" as the District line train was packed during the rush hour.
Prime Minister May said the public should not be alarmed by armed officers on the streets, a rare sight in Britain.
Others chimed in, with May's former chief of staff, Nick Timothy, saying Trump's comment was "so unhelpful from leader of our ally and intelligence partner".
The Metropolitan Police echoed the Prime Minister's concerns, as Mr Trump's comments did not correspond with any information released by the United Kingdom authorities. "It keeps going and going, and we have to be very smart and we have to be very, very tough - perhaps we're not almost tough enough".
Actually, his irresponsibly rapid response to the attack at the Parsons Green station compared with his deeply problematic stance on the white supremacists responsible for the death of Heather Heyer proves Trump only has a voice for the kinds of terrorism that fit his agenda.
This isn't the first time Trump has chimed in quickly after a terrorist attack in Britain since coming into office.
President Donald Trump says the United States must be "proactive" and "nasty" against the Islamic State group. We need the courts to give us back our rights. He tweeted that he would like to expand the travel ban in the country.
Trump's travel ban has been ensnared in the courts since Trump's first attempt to enact the policy in January.
As for the travel ban, A.P. notes that remains tangled in the court systems with the Supreme Court scheduled to listen to arguments on October 10. "We need the Travel Ban as an extra level of safety!" he wrote on June 3. The order might give hope to supporters of the ban, but it may also simply reflect a desire on the part of the justices to maintain the status quo until the justices can hear the case next month.