London mayor Sadiq Khan has "more important things to do" than respond to an "ill-informed" tweet sent by US President Donald Trump after the London terror attack, his office said Sunday.

"The Mayor is busy working... to coordinate the response to this horrific and cowardly terrorist attack," said Khan's spokesman. "He has more important things to do than respond to Donald Trump's ill-informed tweet that deliberately takes out of context his remarks urging Londoners not to be alarmed when they saw more police -- including armed officers -- on the streets."