Islamic State (IS) has claimed responsibility for the explosion in which 29 people were hurt after an Improvised Explosive Device (IED) blasted on a Tube train at the Parsons Green Station.
Soon after the attack, Trump pointed fingers at British police and advised them to be 'proactive'.
In another tweet, he said, "Loser terrorists must be dealt with in a much tougher manner.The internet is their main recruitment tool which we must cut off & use better! (sic)."
Theresa May didn't like Trump's comments. Therefore, during the pool interview when she was asked whether Trump knew something the British public did not, she said, "I never think it's helpful for anybody to speculate on what is an ongoing investigation."
Not only May but her former chief of staff, Nick Timothy, also censured Trump.
He termed Trump's comments unhelpful from Britain's intelligence partner.
"True or not - and I'm sure he doesn't know - this is so unhelpful from leader of our ally and intelligence partner," Timothy tweeted.
Following the attack, Britain has raised threat level from severe to critical.
"The joint terrorism and analysis centre, the independent organisation responsible for setting the threat level on the basis of available intelligence has now decided to raise it from severe to critical," May announced.
The Prime Minister also said military personnel will replace police officers on guard duties, and warned the public would see a greater presence of armed police on the streets.
She, however, urged the public to go about their "business in a normal way."
This is the fourth time that the assessment has been placed at the highest level in the past 11 years.
The IS has claimed responsibility for Friday's Tube train attack.
Quoting security analysts SITE, The Independent reported that a "detachment" from the extremist group was responsible.
"According to a translation by Middle East observer Hassan Hassan, the message on the group's propganda page said: 'A security source to Amaq: the bombing of the IED in the London tube was carried out by a unit affiliated to the Islamic State'," said The Independent report.
British Police and security officials have been investigating to identify the culprits who planted IED in the Tube train.
Hundreds of officers are going through CCTV footage.
Police have also interviewed "tens" of witnesses and received nearly 80 images and videos from the public following an earlier appeal.
Investigators have also been examining the device which blew up on the train.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)