Many observers had been watching to see if the king, who is on his annual summer holiday in Scotland, would end his noticeable silence on the disturbances.
Hundreds of people have been arrested in the near-nightly unrest that hit cities across England and in Northern Ireland and which authorities have blamed on far-right agitators.
Officials say the rioters took advantage of the killings of the girls in the northwestern English coastal town of Southport to launch racist and Islamophobic protests. The suspect accused of the killings was born in Britain.
Traditionally, the monarch does not comment on anything that could cause political controversy.
But in calls with Prime Minister Keir Starmer and police chiefs, the king said he had been “greatly encouraged” by the reaction “that countered the aggression and criminality from a few with the compassion and resilience of the many”.
While extra police have been put on standby, there have been many counter-demonstrations in cities where far-right protests had been planned.
