"We will keep on doing all that we can to keep the British public safe, protecting vulnerable young minds from others' extremist beliefs and promoting the shared values of tolerance, love and respect that make Britain so great," he added.
London's public transport workers also joined local residents in marking the 10th anniversary, observing a minute's silence across the London Underground and the wider Transport for London network.
"No one who works at, or for, TfL will ever forget the events of 7th July 2005. Our thoughts are with the victims, those injured and their families and loved ones at this poignant time," said Peter Hendy, London's Transport Commissioner.
He said the actions of the staff and contractors and the emergency services during the attacks "were nothing short of heroic."
"We will always be proud of how TfL, as well as the Capital as a whole, pulled together and proved its defiance and resilience against terrorism," he noted.
Mike Brown, managing director of London Underground and Rail, said: "What happened 10 years ago will never be forgotten, and neither will the valiant actions of our staff, the emergency services and members of the public, who worked so compassionately to help those in need."
"The people of London showed extraordinary courage and their support and patience as we worked to return the transport network to normal was invaluable," Brown remarked.
On July 7, 2005, explosions in London Underground trains and a bus killed 56 people, including the four suicide bombers, and injured more than 700 others.
The attacks were believed to be the worst terrorist incident in Britain since the 1988 Lockerbie bombing.