"It's awful. Very wicked, to target that sort of thing", the 91-year-old monarch told 14-year-old Evie Mills and her parents.
Health officials said Wednesday that 20 people remained in "critical care" and were suffering from "horrific injuries". Twelve of the injured are aged under 16.
British officials say that have receive assurances from USA authorities that confidential material will be protected.
British Prime Minister Theresa May, who spoke about the matter with U.S. President Donald Trump at a North Atlantic Treaty Organisation summit in Brussels, said the countries' partnership on defense and security was built on trust.
"We will continue in honor of the ones we lost, their loved ones, my fans and all affected by this tragedy", she wrote.
Apparently, the leaks led to a major row between the two countries.
"If appropriate, the culprit should be prosecuted to the fullest extent of the law", he said in a White House statement.
British officials are particularly angry that photos detailing evidence about the bomb used in the Manchester attack were published in The New York Times, although it's not clear that the paper obtained the photos from US officials.
"Until the operation is complete, we can't be entirely sure that it is closed".
Libya said it was working closely with Britain to identify possible "terrorist networks" involved.
Mark Rowley, the UK's most senior counter-terrorism officer, confirmed British chiefs had "received fresh assurances" from their overseas counterparts that they could be trusted with confidential material.
The first leak came on Tuesday after an unnamed USA source told American broadcaster CBS the name of the Manchester suicide bomber Salman Abedi, despite earlier appeals by police in the U.K.to local media to not publish details on the person in order to aid the investigation. Rudd said she had complained to U.S. officials to make sure the flow of information was staunched.
"I think he saw children - Muslim children - dying everywhere, and wanted revenge".
Grande tweeted after the bombing she was "broken" by the attack by British-born Salman Abedi that was claimed by Islamic State.
On his first official trip to Britain as USA secretary of state, Rex Tillerson said "all across America, hearts are broken" by the attack.
Manchester Arena was packed to capacity with teenagers, children, and families, who had all gone out to witness Ariana own the stage and do what she does best.
Abedi, a college dropout who had grown up in the Manchester area, was known to security services because of his radical views.
Manchester police arrested five men and one woman on Wednesday, bringing the total held for questioning to seven, and searched multiple addresses in northern and central England.
Residents were later allowed to return.
Prime Minister Theresa May had cited the possibility of a broader network of plotters on Tuesday night when she raised Britain's alert level from "severe" to "critical" and announced the deployment of troops to guard key sites. Armed police were also deployed on trains for the first time ever.
The attack was the deadliest in Britain since 2005 when four Islamist suicide bombers attacked London's transport system, killing 52 people.
According to the statement, Grande's tour will resume in Paris on June 7.