KABUL, Afghanistan (AP) -- The top U.S. commander in Afghanistan called on his troops to resist any urge to avenge the death of two American soldiers killed in riots over the burning of Qurans at a U.S. base, even as renewed protests Friday claimed at least seven lives.
The anti-American demonstrations by thousands of Afghans who took to the streets after midday prayers were further evidence that President Barack Obama's apology has failed to quiet the outrage over what the U.S. says was the inadvertent destruction of the holy books.
The killing of the two U.S. soldiers and the civil unrest have further strained Afghanistan's relations with the United States. Afghan President Hamid Karzai is trying to negotiate a long-term partnership agreement with the United States to govern the activities of U.S. forces in his country after 2014, when most foreign combat troops will have left or taken on support roles.
The violence against coalition troops also comes at a time when many countries contributing to the force are seeking to accelerate their withdrawal from what has become an unpopular and costly war that has dragged on for more than 10 years.
In Washington, White House spokesman Josh Earnest acknowledged that the burning of Qurans had created "difficult circumstances."
"It is our view that we will work through these difficult circumstances and remain on track to making progress on our goals," Earnest said.
At least 20 people, including the two U.S. soldiers, have been killed in four days of violence.
Protesters have ignored appeals by Karzai, parliamentarians and some clerics for an end to the violence until an investigation into the incident at Bagram Air Field is concluded in coming days.
Afghan officials said seven people were killed around the country Friday by Afghan security forces trying to disperse crowds or responding to gunfire from protesters.
One of the dead was part of a crowd trying to storm a Hungarian military base in northern Baghlan province. Six others were killed in western Herat province, including three people who died when a truck full of ammunition exploded after protesters set it ablaze, the governor's office said.
Anti-American protesters also gathered in several locations around Kabul, including in the city's east, where a demonstrator, his clothes covered in blood, was carried from the scene as about 200 police tried to push the crowd back.
Police sprayed volleys of automatic rifle fire over the heads of protesters chanting "Death to America!" in an effort to prevent them from reaching the defense ministry, located close to the American Embassy.
U.S. Gen. John Allen, who commands all U.S. and coalition troops, traveled late Thursday to the American base in the east where an Afghan soldier opened fire on U.S. troops, killing two Americans.
"There will be moments like this when you're searching for the meaning of this loss. There will be moments like this when your emotions are governed by anger and a desire to strike back," Allen said in comments NATO released Friday.
"Now is not the time for revenge. Now is not the time for vengeance. Now is the time to look deep inside your souls, remember your mission, remember your discipline, remember who you are."
Allen, who was accompanied by Afghan National Army Gen. Sher Mohammed Karimi, told soldiers that "now is how we show the Afghan people that as bad as that act was in Bagram, it was unintentional and American and ISAF soldiers do not stand for this." ISAF is the acronym for the International Security Assistance Force, the formal name of the U.S.-led international military coalition fighting in Afghanistan.
The two U.S. troops were killed during a protest Thursday outside the American base in the Khogyani district of Nangarhar province. Two protesters were killed by Afghan police there before the Afghan soldier turned his gun on U.S. troops. He then fled into the crowd.
Karimi told the U.S. troops that their sacrifice is not wasted.
"It is a rewarding mission and this enemy fighting against us, is not an enemy of Afghanistan, it is an enemy of the whole of humanity," Karimi said.
It was the latest in a rising spate of incidents where Afghan soldiers or police, or militants wearing their uniforms, have shot and killed U.S. and NATO service members.
The unrest started Tuesday, when Afghan workers at the sprawling Bagram air base noticed that Qurans and other Islamic texts were in the trash that coalition troops dumped into a pit where garbage is burned. Some Afghan workers burned their fingers as they tried to salvage some of the books. Afghan government officials said initial reports indicated four Qurans were burned.
U.S. officials said the materials had been taken from a library at Parwan Detention Facility, which adjoins the base, because they contained extremist messages or inscriptions. Writing inside a Quran is forbidden in the Islamic faith, although it was unclear whether the handwritten messages were found in the holy book or other reading materials.
A military official said it appeared that detainees at the prison were exchanging messages by making notations in the texts.
Obama apologized in a letter to Karzai Thursday, expressing "regret and apologies over the incident in which religious materials were unintentionally mishandled."
"We don't care about Obama's apology," said Kamaluddin, a 25-year-old Kabul protester who uses only one name. "We have to protest to be responsible to our God. They are burning our Quran. An apology is not enough."
Associated Press writer Amir Shah and AP photographer Rahmat Gul in Nangarhar and Julie Pace in Washington contributed to this report.