Haji Muhammad Wali, spokesman for the Helmand governor, said the fighters attacked the post on Saturday night in the Bolan district about 7km west of provincial capital, Lashgargah.
The condition of one of the wounded men was said to be serious, the spokesman said.
"We don't how many Taliban were involved in the attack," said Wali. "But we had five soldiers at the post and all of them had been hit," he added.
The Taliban have stepped up attacks in recent months in southern Afghanistan, since it was ousted from power in late 2001 by US-led forces.
UN condemns attack
More than 300 people, including aid workers, US soldiers and many Taliban soldiers, have been killed in the insurgency across Afghanistan since August.
The United Nations, meanwhile, condemned an attack near the southern town of Kandahar on Saturday in which a driver from an Afghan demining agency was wounded when assailants opened fire on his vehicle.
The attacks came ahead of the arrival of US Deputy Secretary of State Richard Armitage in Afghanistan on Sunday for talks with Afghan leaders on security and aid for reconstruction efforts. Armitage is accompanied by Assistant Secretary of State Christina Rocca.