Officials in the city of Qalat in Zabul Province said seven police officers were injured by thrown stones, and three protesters were wounded.
Police are reported to have opened fire in a bid to control the protesters.
The incident came after four people were reported killed by security forces on 7 February in Afghanistan when cartoon protests also turned violent.
Earlier, the Organization of the Islamic Conference, the United Nations, and the European Union issued a joint call for urgent dialogue to defuse Muslim anger over the Danish caricatures.
The cartoons were originally published in September, but have recently been reprinted in newspapers around the world.
In a written statement, the three organizations said they understand the deep hurt and widespread indignation felt in the Muslim world over the cartoons, but said recent violent acts have surpassed the limits of peaceful protest.
(compiled from agency reports)
Clash Of Cultures
Indian-born writer Salman Rushdie (epa file photo)
The furor raised by the publication in Europe of cartoons believed by many Muslims to be insulting to Islam is far from being the first time that Western notions of freedom of expression have clashed with Islamic sensibilities. Below are a few of the major incidents in this long-running tension.
2005: London's Tate Britain museum removes from exhibition the "God Is Great #2" sculpture by John Latham for fear of offending Muslims, citing the "sensitive climate" after 7 July suicide bombings in London. The sculpture piece consists of three sacred religious texts -- the Koran, the Bible, and the Talmud -- embedded in a sheet of glass.
2004: Dutch filmmaker Theo van Gogh is murdered after release of his film "Submission" about violence against women in Islamic societies. Ayaan Hirsi Ali, a Somali-born member of Dutch parliament who wrote script, plans another film about Islam's attitude to gays. She has also received death threats.
2002: Nigerian journalist Isioma Daniel incenses Muslims by writing in "This Day" newspaper that Prophet Muhammad would have approved of the "Miss World" contest and might have wed a beauty queen. Muslim-Christian riots in northern city of Kaduna kill 200. Daniel flees Nigeria after a fatwa urges Muslims to kill her.
1995: An Egyptian court brands academic Nasr Hamed Abu Zaid an apostate because of his writings on Islam and annuls his marriage on grounds that a Muslim may not be married to an apostate. Abu Zaid and his wife move to the Netherlands.
1994: Taslima Nasreen flees Bangladesh for Sweden after court charges her with "maliciously hurting Muslim religious sentiments." Some Muslims demand she be killed for her book "Lajja" (Shame), banned for blasphemy and suggesting free sex.
1989: Iranian leader Ayatollah Ruhollah Khomeini calls on all Muslims to kill British author Salman Rushdie for blasphemy against Islam in his book "The Satanic Verses."
(compiled by RFE/RL)
A thematic webpage devoted to issues of religious tolerance in RFE/RL's broadcast region and around the globe.