Afghan President Hamid Karzai speaks to members of the audience during the concluding day of the Loya Jirga (Grand assembly) in Kabul, Nov. 24, 2013. (S. Sabawoon/EPA)

Afghan President Hamid Karzai accused the United States of launching a drone strike that killed a 2-year-old child Thursday and vowed not to sign a long-term security agreement if similar attacks continue.

In a statement, Karzai said a suspected U.S. “pilot-less aircraft” fired into a house shortly before noon in Helmand province, killing the child and wounding two women. He said the information was relayed to him by Mohammad Naem, the governor of the province.

In a statement Friday morning, the U.S.-led international coalition confirmed it had conducted the airstrike while targeting an “insurgent riding a motorbike.”

But the coalition said it has also received reports that the airstrike mistakenly killed a child in addition to the intended target.

The International Security Assistance Force “deeply regrets any civilian causalities caused by this airstrike yesterday,” the coalition said, noting that two women may have also been injured in the strike. “ISAF is committed to ensuring that all measures are taken to prevent civilian causalities.”

The coalition vowed to immediately launch an investigation and said it “will work with Afghan officials to determine what happened and why.”

“We extend our deepest sympathies to the families and loved ones of those killed or wounded,” the statement said.

The allegations are likely to stoke tension over Karzai’s reluctance to endorse a plan that would allow several thousand U.S. troops to remain in Afghanistan after 2014.

After a year of negotiations, the Obama administration thought it had finalized an agreement with Karzai last week to allow up to 15,000 foreign troops to stay to train and assist the military.

But Karzai has been reluctant to sign it, saying he first wants assurances that the United States won’t meddle in Afghan elections next year, will cease military raids on Afghan homes, and will help start peace talks between Karzai’s government and Taliban insurgents. For the latter, he has demanded that the United States release 17 Afghan prisoners from the U.S. detention center at Guantanamo Bay, Cuba. Now, Karzai has added a reduction of U.S. airstrikes to his list of demands.

“This attack shows that American forces are not respecting the life and safety of Afghan people’s houses,” he said in the statement. He added, “For years, our innocent people have become victims of the war under the name of terrorism, and they have had no safety in their homes.”

He said he won’t sign the security agreement if such “oppressions by foreign forces continue.”

It was unclear from his statement whether he was calling for an end of all drone strikes or just attacks that target homes.

The alleged death of the child comes one week after Karzai accused U.S. Special Operations forces of killing two Afghan civilians during a raid on a house in eastern Afghanistan. Karzai’s assertion angered coalition commanders, who insisted that the men were “armed insurgents.” They accused Karzai of using “allegations of civilian deaths for political purposes.”

But Karzai cited the incident as justification for his decision to delay the signing of the agreement. During a meeting Monday with U.S. national security adviser Susan E. Rice, Karzai demanded that American troops immediately stop entering the homes of Afghan citizens, his spokesman said.

The Obama administration responded by saying that if the agreement is not signed by the end of the year, it will have no choice but to begin preparing for a full withdrawal of U.S. forces from Afghanistan next year.

“It’s not something that we want to foresee or want to pursue,” U.S. Ambassador James B. Cunningham told Afghan reporters Wednesday. But, he added, “it could be a consequence of decisions that your government takes or doesn’t take.”

Karzai’s stance has befuddled Western analysts and is a growing concern for many Afghan political leaders, who say he is endangering Afghanistan’s security because the agreement includes $4 billion in annual U.S. and coalition funding for the Afghan military.

On Sunday, a council of 2,500 Afghan tribal leaders and civic activists endorsed the agreement and called on Karzai to quickly sign it. In his statement Thursday, Karzai accused the United States of undermining the spirit of that gathering by launching the airstrike that he said killed a child.

Sayed Salahuddin in Kabul contributed to this report