In Tehran, dozens of Iranian protesters pelted the Danish embassy with stones and petrol bombs, witnesses said. Riot police guarded the embassy.
Muslims were angered when Danish television stations aired footage of members of the youth wing of the anti-immigrant Danish People's Party (DPP) drawing cartoons mocking the Prophet. Iran has condemned the broadcast.
In September last year, the Danish daily Jyllands-Posten published cartoons that Muslim clerics denounced as blasphemous, sparking protests early this year in which more than 50 people were killed in Asia, Africa and the Middle East.
"(The latest cartoon issue is) smouldering around in the Muslim world. We hope it will die out but we don't know if it will pass," said Danish Foreign Minister Per Stig Moller.
Most Muslims regard any depiction of the Prophet as offensive.
"Don't forget that the (last) cartoon crisis broke out four months after the drawings were first published, so I can't guarantee anything," said Mr Moller.
This time Danish Prime Minister Anders Fogh Rasmussen acted quickly and condemned the behaviour of the DPP members. He was criticised earlier this year for refusing to apologise for the previous cartoons of the Prophet.
The DPP is not a member of the ruling coalition but supports the government in parliament.
Mr Moller said he had talked to Iranian and Syrian leaders and that he hoped the government's efforts to calm anger in the Muslim world would bear fruit.
Protests erupt
Witnesses said the protesters outside the Danish embassy in Tehran chanted "Down with Zionists" and "God praise the party of God".
The protesters set fire to a tyre next to the embassy compound wall but fire-fighters put it out.
Denmark's ambassador to Tehran was summoned to the Foreign Ministry on Monday about the television footage.
Iranian President Mahmoud Ahmadinejad has condemned those involved in the footage as "low life".
More than 230 legislators in Iran's 290-seat parliament urged President Ahmadinejad on Tuesday to cut Iran's trade ties with Denmark, the semi-official Mehr News Agency reported.
"The past attempts of the Danish government regarding this insult (to the Prophet) have been repeated, this time by the visual media," said Mehr.
Total Danish yearly exports to Muslim countries are about 10 billion crowns ($A2.4 billion), or roughly 2 per cent of all exports.