On Easter Sunday, more than 70 people, mostly women and children, were killed in an apparent suicide bombing in a Lahore park.
Jamaat-ur-Ahrar, a breakaway faction of the Pakistani Taliban, claimed responsibility for the bombing and said it targeted Christians.
"The United States will continue to support the Pakistani government as they try to confront and combat the extremist element within their own country," White House spokesman Josh Earnest told reporters.
Earnest called Sunday's attack "grotesque and chilling," and noted that the United States will continue to support the Pakistani government's efforts to surpass terrorists.
Sunday's attack, along with the 2014 massacre of school students and teachers in Peshawar, shows that extremism and terrorism pose a serious threat to Pakistan, Earnest observed.
On Monday, Pakistani officials said they will launch military operations against Jamaat-ur-Ahrar in the province of Punjab.