The Republican told reporters that Afghan national forces are fighting bravely, but suffering heavy losses in the field.
American and international troops have already stopped playing a combat role, remaining as trainers for local forces. The international numbers will be reduced further at the end of 2016. But McCain said reductions should be based on conditions on the ground.
"With the rise of ISIS and the distinct fighting season that is marked this year, the threat environment continues to evolve in ways that clearly, in my view, demands a reassessment of the administration's current calendar-driven drawdown of U.S. forces with a plan that must be based on conditions on the ground," McCain said.
Both Afghan President Ashraf Ghani and McCain deem terrorism and extremism as a threat to the stability of Afghanistan, the region and the world, and stressed the importance of continuing efforts to fight it, a statement from the presidential palace said.
Meanwhile, Afghan lawmakers rejected Ghani's nominee for defense minister, a position that has remained empty for more than nine months amid some of the toughest fighting since the Taliban insurgency began 14 years ago. Masoom Stanekzai received just 84 out of the 107 votes needed for parliamentary approval.
Stanekzai is better known as a peacemaker, having led the High Peace Council negotiating body charged with ending the conflict with the Taliban. He has been serving as the country's top defense official in an acting capacity.