The draft proposal would create a force of up 15,500 troops that would train Afghan troops after 2014, The New York Times reported.
The plan currently suggests that 9,500 of the troops would likely be U.S. forces, although no final decisions have been made.
Pentagon spokesman George Little denied reports the United States would contribute 8,000-12,000 service personnel. He said those figures were discussed as the potential size of the "overall" NATO mission.
In its present state, the plan foresees coalition forces operating out of a headquarters in Kabul but connected to training bases in four regions of the country.
Afghan troops would be trained by conventional forces at the Kabul headquarters, with Special Operations forces mentoring at the training bases.
Some 66,000 U.S. troops are stationed in Afghanistan and U.S. President Barack Obama has said 34,000 of the soldiers will be withdrawn by February 2014.
About 37,000 NATO and coalition forces are in Afghanistan.