Trump, who was in Bethlehem where he was meeting Palestinian counterpart Mahmoud Abbas, said: "I extend my deepest condolences to those so terribly injured in this terrorist attack and to the many killed."
He said "evil losers" and a "wicked ideology" were responsible.
"This wicked ideology must be obliterated - and I mean completely obliterated - and the innocent life must be protected. All civilised nations must join together to protect human life and the sacred right our citizens to live in safety and in peace," he said.
France's new President Emmanuel Macron offered his sympathies to the British people and said: "We are fighting terrorism together."
Russian President Vladimir Putin called the act a "cynical, inhumane crime".
"We strongly condemn this cynical, inhumane crime. We hope that its masterminds will not escape the punishment they deserve," he said.
German Chancellor Angela Merkel said: "This suspected terrorist attack will only strengthen our resolve to continue to work together with our British friends against those who plan and carry out such inhumane deeds."
"These cowardly attacks will only strengthen our commitment to work together to defeat the perpetrators of such vile acts," he said.
Israeli Prime Minister Benjamin Netanyahu said his government "strongly condemns the terrible terror attack".
"Terror is a global threat and the enlightened countries must act together to defeat it in any place," he said.
Australian Prime Minister Malcolm Turnbull said the attack was "especially vile, especially criminal, especially horrific because it appears to have been deliberately directed at teenagers."
Canadian Prime Minister Justin Trudeau tweeted: "Canadians are shocked by the news of the horrific attack in Manchester tonight."
Japanese Prime Minister Shinzo Abe condemned the attack and said he was "deeply shocked" that "this appalling act of terrorism".
"On behalf of the government of Japan and the Japanese people, I would like to express my heartfelt condolences to the victims and extend our sympathies to those who have been injured," he said.
Chinese President Xi Jinping said: "The Chinese people are firmly standing together with the British people at this difficult time."
Malaysian Prime Minister Najib Razak, said he was appalled by the "barbaric and cowardly attack on innocent concertgoers".
"At this time of heartbreak, Malaysia stands united with Britain. We must be firm, determined and ready to confront terror swiftly and decisively wherever and whenever it manifests itself. We must never surrender," Najib said.
Disclaimer: No Business Standard Journalist was involved in creation of this content
