The Taliban claimed responsibility for the attack which comes as President Hamid Karzai deliberates over an agreement allowing U.S. forces to stay in the country beyond 2014.
ISAF put the death toll at three service members. It gave no more details.
A Taliban spokesman claimed responsibility in a message on his Twitter account.
“A number of foreign forces were killed and wounded and many vehicles were also destroyed,” the militant spokesman said.
Many Afghans, including a gathering of 3,000 tribal leaders and other prominent people, have urged Karzai to sign the U.S. pact quickly as they worry about security after 2014 when most foreign forces are leaving.
Karzai says he does not want to sign until after a presidential election scheduled for April next year and unless the United States fulfils a number of his demands.