The President used his third tweet about the attack to push his so-called Muslim travel ban in the United States, saying it should be "far larger, tougher and more specific".
"Loser terrorists must be dealt with in a much tougher manner", he wrote.
Deputy Foreign Minister Tzipi Hotovely condemned the attack as well, saying "Israel condemns the #terror attack in London".
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"Another attack in London by a loser terrorist".
The bomb exploded on a packed train during morning rush hour Friday, leaving 29 people wounded but no one with life-threatening injuries.
The Prime Minister's response was echoed by her former chief of staff, Nick Timothy, who tweeted: "True or not - and I'm sure he doesn't know - this is so unhelpful from leader of our ally and intelligence partner".
Scotland Yard said it was "too early" to confirm the cause of the blast during the Friday morning rush-hour, which saw 18 people taken to hospital.
On 3 June, the day of the terrorist attack on London Bridge, the president tweeted: "We need to be smart, vigilant and tough".
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Trump responded on Twitter: "At least 7 dead and 48 wounded in terror attack and Mayor of London says there is 'no reason to be alarmed!'".
In short remarks to reporters, Trump said he had been briefed on the explosion but did not elaborate on what he meant in his reference to Scotland Yard.
A police spokesperson told CNN Trump's comment is "pure speculation given we don't know who is involved".
Sadiq Khan, the Muslim mayor of London, said that his city "utterly condemns the ugly individuals who attempt to use terror to harm us and destroy our way of life". "The internet is their main recruitment tool which we must cut off & use better!" And, he said, his administration was doing more to combat ISIS than the Obama White House.
But perhaps his most freakish response came in this television interview aired from outside the White House.
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Moreover, one of the GOP senators who wound up supporting skinny repeal, Rand Paul, has announced opposition to Graham-Cassidy. That does not leave a lot of time, but Turner said she believes it is possible.
Trump concluded, "Must be proactive & nasty!"