US President Barack Obama and his Afghan counterpart Hamid Karzai have held an hour-long video conference talk in which they vowed to continue working together to combat the Taliban.
Mr Obama also repeated US commitment to working with Afghans on stability and security, the White House said.
June was the deadliest month for US forces in Afghanistan since the conflict began in 2001.
Analysts say mounting casualties have eroded support for the war in the West.
In a statement, the White House said: "Both leaders agreed to continue in our shared efforts to combat violent extremism, protect the Afghan people, improve governance, and deliver basic services, particularly at the local level."
Mr Obama also repeated the US commitment to partnering the Afghan people in trying to ensure that Afghanistan will be stable and secure.
The US envoy to Kabul, Karl Eikenberry, and top military commander General David Petraeus also participated in the video conference, the White House said.
Correspondents say relations between Mr Obama and Mr Karzai have rarely been easy - particularly after Mr Karzai was re-elected last year in an election widely condemned as corrupt by Western observers.
Washington gave Mr Karzai the red-carpet treatment during a state visit earlier this year in a bid to smooth relations.
But Mr Karzai has continued to be frank in his criticism of Western powers.
Last month, he said the West was not doing enough to combat the Pakistani Taliban.
And he also said that leaked information from the US whistle-blowing website Wikileaks had endangered the lives of Afghans working with American forces.