Hezb-e-Islami, a main insurgent group led by former Prime Minister Gulbuddin Hekmatyar, is considered second only to the Taliban in Afghanistan.
Habib-ur-Rahman, the rebel leader's son, told the BBC that Hezb-e-Islami was proposing a cease-fire agreement for the benefit of Afghanistan.
"If they remain in their bases, then we will not attack them," he said of the U.S. forces in Afghanistan.
Washington increased the troop presence in Afghanistan as part of a revised war strategy spelled out in December. European leaders, however, said they were coming to the conclusion that a military solution is unlikely in the country.
"All Afghan groups agree that war is not the solution," added Rahman. "But the Americans are sending 30,000 more troops in."
He said a "rational plan" for the end of the Afghan war meant a pull back for U.S. forces, new elections and a government that included anti-Western elements like his group.
His comments follow statements from Taliban leader Mullah Omar who said there was no chance of peace with the Afghan government.
World leaders head to Lisbon, Portugal, this week to discuss Afghanistan at a NATO summit.
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