Mayor Livingstone has struck a defiant tone, after he rushed back to London from Singapore, where his city was awarded the 2012 Olympic games two days earlier.
Mr. Livingstone says he sees no link between either the Olympics or the Iraq war and the terrorist bombing that hit three London subway trains and a bus on Thursday.
Authorities suspect Islamic militants, perhaps linked to the al-Qaida terrorist network, carried out the bombings.
Mayor Livingstone says the bombers clearly oppose the freedom and multicultural ambiance of London, which is home to eight million people from every corner of the world.
"I say to those who planned this dreadful attack, whether they are still here in hiding or somewhere abroad, watch next week as we bury our dead and mourn them, but see also in those same days new people coming to this city to make it their home, to call themselves Londoners, and doing it because of that freedom to be themselves," said Mr. Livingstone.
London police are still searching for clues and bodies at four bombsites. Police commissioner Ian Blair is appealing for public assistance in the search for the perpetrators. And he is playing down speculation that a suicide bomber attacked the bus.
The commissioner says a number of foreign citizens were wounded, including people from Australia, China, Poland, Portugal and Sierra Leone.
There are questions about how this attack succeeded when the police successfully thwarted earlier suspected terrorist plots. Home Secretary Charles Clarke told British television the job is difficult.
"Well, the fact is, we have very effective intelligence services, but we did not predict this particular act at this particular time," said Mr. Clarke. "And the reason for that is that we are always looking for a very small number of evil needles in a very, very large haystack, which is the city of London."
Meanwhile, hundreds-of-thousands of London commuters got back on board buses and subway trains for the Friday morning rush hour. There was a mood of nervousness, but determination among most commuters to get on with their lives and work.
Mayor Livingstone says he will ride to work on the subway on Monday, as he normally does, and he is urging all Londoners to follow his example.