No coalition forces were killed in the attack on Combat Outpost Sayed Abad in Wardak province, a statement said. An Afghan official earlier said there was at least one civilian killed.
NATO said none of the injuries was life threatening. It did not say how many people were injured in the explosion, which came on the eve of the 10th anniversary of the Sept. 11 terrorist attacks against the United States.
"Most of the force of the explosion was absorbed by the protective barrier at the outpost entrance and though there were a significant number of injuries, all are being treated and none is immediately life threatening," NATO said.
The attack was carried out by a Taliban suicide bomber who detonated a large bomb inside a truck carrying firewood, NATO said.
The blast "damaged the compound entrance and was not followed-up by any subsequent attacks. The impact to the compound is readily repairable and operations are continuing," NATO said.
The attack came hours after the Taliban vowed to keep fighting U.S. forces in Afghanistan until all American troops leave the country and stressed that their movement had no role in the Sept. 11 attacks.
In a statement emailed to media, the Taliban accused the United States of using the Sept. 11 attacks as a pretext to invade Afghanistan and said the international community was responsible for killing thousands of Afghans during the invasion and ensuing occupation.
"Each year, 9/11 reminds the Afghans of an event in which they had no role whatsoever," the Taliban said. "American colonialism has shed the blood of tens of thousands of miserable and innocent Afghans."
The United States and its allies invaded Afghanistan on Oct. 7, 2001, after the Taliban, who then ruled the country, refused to hand over Osama bin Laden.
The late al-Qaida leader was at the time living in Afghanistan, where the terror network had training camps from which it planned attacks against the U.S. and other countries.
"The Afghans have an endless stamina for a long war," the statement said. "Through a countrywide uprising, the Afghans will send the Americans to the dustbin of history like they sent other empires of the past."
The statement was issued by the Islamic Emirate of Afghanistan, the official title used by the Taliban when they ruled the country.
Although the Taliban were swiftly driven from power by the U.S.-led coalition, they managed to use the years of the Iraq war -- when America focused its military strength on the conflict against Saddam Hussein -- to regroup, rearm and reorganize.
They began winning back ground lost to the international military coalition until President Barack Obama decided to send in 30,000 more troops last year to help.
Although there have been some coalition gains in the Taliban's traditional southern strongholds, violence has not abated around the country.
The U.S. has begun withdrawing some of its 100,000 troops and will send home 33,000 by the end of next year. The international military coalition has already begun transferring security responsibilities to newly trained Afghan forces with the aim of removing all their soldiers by the end of 2014.
In another development, NATO and Afghan forces arrested a former inmate at the U.S. military prison at Guantanamo Bay.
A tribal elder said Said Amir Jan was arrested during the same raid in which another former Guantanamo detainee was killed a week ago in the eastern city of Jalalabad. But word of his arrest only emerged Saturday.
Jan, 30, was suspected of being a "low-level member of al-Qaida" before he was sent to Guantanamo in 2003, according to his military file, made public by WikiLeaks.
He was assessed as medium risk in 2005 by military officials and sent back to Afghanistan in 2007.
The man killed in the raid was Sabar Lal Melma. Soldiers shot him after he confronted them with an AK-47.
NATO and Afghan officials have not commented on the identities of anyone arrested in the Sept. 2 raid.
But tribal elder Rohullah Wakil, a friend of the slain man and himself a former Guantanamo detainee, said Saturday that Jan and two other people -- Melma's cousin and a man named Dairan -- were arrested.
NATO raided Melma's house because he was suspected of organizing attacks in eastern Kunar province and funding insurgent operations after he was released from Guantanamo in 2007.
NATO officials described Melma as a key al-Qaida ally.