Barack Obama said he was “heartbroken” by the Manchester attack that killed 22 people and he hoped he will be able to use his influence to bring young people together in the face of terrorism.
“At a time, when the world is a very complicated place, when we can see the terrible violence that took place just recently in Manchester," the former US President told a crowd of tens of thousands at an event in the German capital Berlin about democracy and global responsibility.
Standing alongside German Chancellor Angela Merkel, he added: “We had a moment back stage to send a message to the people of Manchester and tell them how heartbroken we are, about the loss of life and to grieve with the families."
Mr Obama told the crowd that the pair had taken the time before entering to the stage to send a message of condolences to the people of Manchester.
In a video message with Ms Merkel and the Archbishop of Canterbury Justin Welby, Mr Obama praised the people of Manchester for its "faith and resolve" and told them "the entire world" stood in solidarity with them.
He said: "As the father of two daughters, I am heartbroken by this extraordinary tragedy that has occurred in Manchester. To all the families that have been affected, to those that are still recovering, to those who lost loved ones, it is unimaginable to think about the cruelty and the violence the city of Manchester has suffered.
"My thoughts and prayers with all of you, there are families all around the world, who are grieving with you. What I also want to emphasise though is through faith and resolve the character of the people of Manchester has shown itself with the kindness and the ways in which you were assisting each other. And just know that the entire world is in solidarity with you right now."
Speaking at the event, Ms Merkel said the people of Germany stood side by side with Manchester and all the grieving families from the horrific attack.
Mr Obama announced last month his first post-presidential project will be helping young people get active in politics.
He told the Berlin crowd that this was a time “of great opportunity” to inspire a new generation of leaders.
“My hope is that now, although I’m longer President, hopefully I have a little more influence to help more young people to deal with some of some of these challenges and encourage a new generation of leadership, so that we can marginalise those you will try to divide and bring together more and more people, who can bring us together around a common good.”
He also praised Ms Merkel as someone, who had done "outstanding work" to defend the values of liberal democracy they both shared.
"We have to push back against those trends that would violate human rights or suppress democracy or restrict individual freedoms,” he said.
