Police in Pakistan have fired tear gas to disperse at least 3,000 students demonstrating against cartoons satirising the Prophet Muhammad.
The protests in Peshawar were the first to turn violent there
Sixteen people were held for damaging public property in the protest in the north-western city of Peshawar.
Students also smashed hoardings advertising the Norwegian telecom giant, Telenor, and chanted "Death to America" and "God is Great".
The controversial cartoons were first published in Denmark last year.
They have sparked protests across the Muslim world.
Denmark's Prime Minister Anders Fogh Rasmussen on Monday again tried to soothe the row, insisting his nation was "an open and tolerant society, a tolerant society which respects all faiths".
The European Union's foreign policy chief, Javier Solana, was also trying to build bridges.
He told the head of the Organisation of the Islamic Conference in Jeddah, Saudi Arabia, that there was never any intent to cause offence.
In other developments:
- In response to the row, popular Hamshahri newspaper in Iran launches a contest for cartoons of the Holocaust
- Chechen strongman Ramzan Kadyrov warns that members of Danish NGOs may be the victims of "revenge attacks" there if Denmark does not apologise
- Thousands of students of Egypt's al-Azhar University protest against the cartoons at campuses in Cairo and in the southern city of Assiut
- Hundreds of Palestinian students protest in the West Bank city of Hebron shouting "Death to Jews and Denmark".
The protests in Peshawar were the first there to turn violent, although there have been many since the controversy erupted at the end of last month, the BBC's Haroon Rashid in the city says.
Shopkeepers pulled down their shutters and shoppers abandoned the city's main bazaar as protesters went on the rampage, he says.
In Islamabad, President Pervez Musharraf said newspapers that printed the cartoons were "oblivious" to the consequences for peace and harmony in the world.
"I don't see how any civilised person can take the issue of freedom of press to hurt the feelings of such a large population of the world," he told visiting journalists.
"Whether an extremist or a moderate or an ultra-moderate, we will condemn it."
At least 12 people died in demonstrations last week against the cartoons in Afghanistan.
The cartoons include an image portraying Muhammad with a bomb in his turban. Islamic tradition explicitly prohibits any depiction of Allah and the Prophet.
The cartoons were first published by Danish newspaper Jyllands-Posten in September, but have since been reprinted in several other European publications.
Denmark has temporarily shut its missions in Indonesia, Iran and Syria and urged its nationals to leave Indonesia over fears they may be targeted in the row.
Mr Rasmussen, the Danish premier, met members of a new association called "Democratic Muslims" in a fresh effort to defuse the row.
He told reporters there had been "false pictures, false stories, false rumours of Denmark".
In Jeddah, Mr Solana met Ekmeleddin Ihsanoglu, head of the Organisation of the Islamic Conference and afterwards told reporters: "In the EU we feel a profound respect yesterday, today and tomorrow, and we never wanted in any case to offend their feelings".
Mr Ihsanoglu has called on the EU to pass laws banning blasphemy.