A 15,000-strong joint force of Afghan, Nato and US troops is battling the Taliban in Marjah, where the fighters have been in control for years.
The total number of civilians killed in Operation Moshtarak has risen to 16, and the funeral of a civilian said to have been killed in a Nato raid four days ago was held on Saturday.
Eric Tremblay, the Isaf spokesman, said "coalition forces" had made civilians' safety their priority.
"General Stanley McChrystal [the commander of the international forces] has made it quite clear to our coalition partners and the Afghan national security forces that ... the strategy is to protect the population; it is about separating the insurgency from the population," Tremblay told Al Jazeera from Kabul.
Foreign troop deaths
Against this backdrop of tension over civilian deaths, Nato announced on Sunday that two foreign soldiers had died, though neither was involved in Moshtarak.
In two brief statements, Isaf said both soldiers were killed on Saturday, one in the country's east and the other in the south.
Isaf did not give the nationality of either soldier, according to policy.
It said the soldier killed in the south died as a result of an improvised bomb attack.
US marines and Afghan soldiers continued to advance through poppy fields under gunfire from Taliban fighters shooting from mudbrick homes and compounds where families huddled in terror, the AP news agency reported.
A total of 24 foreign troop deaths have been announced since the launch of Moshtarak, most of them caused by improvised explosive devices.
The Marjah operation is a major test of a new Nato strategy that stresses protecting civilians over routing fighters as quickly as possible.
It is also the first major ground operation since Barack Obama, the US president, ordered 30,000 reinforcements to Afghanistan to curb the rise of the Taliban.
Nato officials say a civilian Afghan administration is to be installed once Marjah is secure. Also, public services will be restored and aid provided to try to win the loyalty of the population and prevent the Taliban from returning.
As Operation Moshtarak entered its second week, US marines and Afghan soldiers faced hours of sporadic but intense gunfire from the Taliban.
Snipers shot from compounds where families had sought shelter and troops crouched for cover in muddy ditches, firing rifles, machine guns, and grenades as Taliban bullets whizzed by.
US-led troops have been pushing south from the town centre against a pocket of Taliban fighters.
A Nato statement said fighting was raging in the northeast and west of the town "but insurgent activity is not limited to those areas".