NATO-led International Security Assistance Force (ISAF) says it has restricted joint operations with Afghan forces, fearing the rise in insider attacks.
ISAF said in a statement on Tuesday that joint operations with Afghan forces would only be conducted at the battalion level.
Cooperation with smaller units of Afghan troops need to be "evaluated on a case-by-case basis and approved by RC (regional) commanders,” the statement added.
The decision was made due to the increase in the number of the so-called "green-on-blue" attacks in which Afghan soldiers turned their weapons on US-led troops in Afghanistan.
More than 51 foreign soldiers have been killed in more than 30 green-on-blue attacks carried out by Afghan troopers since the beginning of this year.
"This guidance was given at the recommendation of, and in conjunction with, key Afghan leaders," said a US military officer on condition of anonymity.
"This will likely lead to adjustments in exactly how, when and where ISAF troops operate, especially during the current period of heightened tension," the officer said.
Meanwhile, statistics by the independent website icasualties.org show that at least 336 foreign troops, most of them Americans, lost their lives in Afghanistan so far in 2012.