Iranian President Mahmoud Ahmadinejad strongly condemned on Wednesday what he called the "savage" crackdown by British police on rampaging youths, the state television's website reported.
"This savage treatment of people is absolutely unacceptable, and British statesmen must hear the voice of the people and grant them freedoms," Ahmadinejad was quoted as saying.
"British politicians should look to help their own people instead of invading Afghanistan, Iraq and Libya to plunder their oil."
Ahmadinejad said part of the British public has "lost its patience and become frustrated," and urged London to "get on the people's side and change their management, instead of using such approaches."
He criticised the UN Security Council for remaining "silent" over the developments in Britain, which is experiencing its worst unrest in decades.
Riots raged into a fifth day on Wednesday as youths ran amok in Manchester and the industrial Midlands, but London was quiet after British Prime Minister David Cameron boosted the police presence in the capital to 16,000.
He said after meeting top security officials a "fightback" had begun against Britain's worst riots in a generation, as he authorised the use of water cannon for the first time outside Northern Ireland.
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Scotland Yard said early on Wednesday that 768 people had been arrested and 111 police officers have been injured in the disorder.
"Even if one hundredth of these crimes were to happen in countries opposed to the West, the United Nations and other organisations claiming to defend human rights would vehemently decry it," Ahmadinejad added.
"The stage has now been set for testing the UN Security Council to see whether it will condemn one of its own permanent members," he added.
Iranian foreign ministry on Wednesday issued a travel warning for its citizens not to visit Britain.
"It is requested that Iranian citizens not travel to Britain in the current situation and if there is a necessity for the trip to avoid the restive areas," said the statement on the ministry's website.
The ministry also asked Iranians living in Britain to refrain from going to the "restive areas in order to be safe from any possible danger and harm."
In 2009, Britain and other Western countries condemned Tehran for violently crushing protests that followed the controversial re-election of Ahmadinejad.
Iran denounced the Western condemnations as meddling in its internal affairs.
Dozens of people were killed in the opposition demonstrations protesting what they said was massive election fraud. Thousands more were arrested, several hundred of whom were handed long prison terms.