Fresh clashes between police and protesters, angry over a film apparently made in the United States that mocks Islam, erupted on Friday outside the U.S. embassy in Cairo, an Agence France Presse reporter said.

The protesters, many in their teens and moving around in small clusters, pelted police with stones who responded by firing tear gas.

Egyptian President Mohamed Morsi reiterated during a visit to the EU on Thursday that Syrian President Bashar Assad must step down as "a president that kills his own people is not acceptable."

At a news briefing, Morsi interjected to state "this is completely agreed upon" when European Commission President Jose Manuel Barroso told reporters after talks between the two sides that "we are also adamant that Assad should go."

An Egyptian court on Thursday sentenced former Prime Minister Ahmed Nazif to three years in prison and to pay a fine of nine million Egyptian pounds ($1.5 million) for illegal enrichment.

Nazif, who left his post in late January 2011 at the start of a popular revolt against then President Hosni Mubarak, was accused of abusing his post to make illegal gains, the official MENA news agency reported.

Egypt's Islamist President Mohammed Morsi Thursday slammed "attacks" on the Muslim prophet Mohammed in a film on Islam that sparked an outcry in Egypt, while also stressing that he condemned violence.

"We Egyptians reject any kind of assault or insult against our prophet. I condemn and oppose all who... insult our prophet," Morsi, on an official visit to Brussels, said in remarks broadcast by Egyptian state television.

Gaza's Hamas Prime Minister Ismail Haniya has postponed until next week a Cairo trip for top-level talks with his Egyptian counterpart Hisham Qandil, a spokesman said Thursday.

Haniya had been scheduled to travel to Egypt on Thursday for discussions on security in the wake of an August 5 attack which killed 16 Egyptian border guards in the northern Sinai, which borders the Gaza Strip and Israel.

Police used tear gas as they clashed on Thursday with a stone- and bottle-throwing crowd protesting outside the U.S. embassy in Cairo at a film mocking Islam, witnesses and the interior ministry said.

The health ministry said 13 people were injured during sporadic clashes through the night outside the embassy, where on Tuesday thousands of protesters tore down the Stars and Stripes and replaced it with a black Islamic flag.

U.S. President Barack Obama called the leaders of Egypt and Libya to discuss security cooperation following the violence in Cairo and Benghazi, the White House said Thursday.

Obama urged Egypt to uphold its commitments to protect U.S. diplomats and called on Libya to work with U.S. authorities to bring those behind the deadly attack on the U.S. consulate, which killed the U.S. ambassador, to justice.

The Palestinian Hamas movement on Wednesday condemned an anti-Muslim film that has sparked deadly riots, as a handful of Gazans burned U.S. flags to protest against the movie.

The low-budget film, "Innocence of Muslims," portrays Muslims as immoral and gratuitously violent. It sparked protests in Egypt and Libya, where rioters attacked the U.S. consulate in Benghazi, killing the ambassador and three others.

President Barack Obama Wednesday condemned the "outrageous" attack which killed four Americans including the U.S. ambassador in Libya but vowed it would not break America's bond with the liberated nation.

In a somber statement in the White House Rose Garden, Obama paid tribute to Ambassador Chris Stevens and his colleagues, killed when an Islamist mob, angered by reports of a film deemed insulting to Islam, stormed the U.S. consulate in Benghazi.

Egypt's government on Wednesday denounced a film deemed offensive to Islam that sparked fury in Egypt and Libya, calling on Egyptians to exercise restraint.

"The film is offensive to the Prophet and immoral," the cabinet said in a statement read by Prime Minister Hisham Qandil at a news conference.