Members of the al-Mahdi Army were deployed around the house after the US and Iraqi forces withdrew on Tuesday.
The correspondent quoted a US military spokesman denying surrounding al-Sadr's house, saying the occupation troops were only responding to clashes that erupted in Najaf after a US patrol came under gunfire.
An Iraqi woman was killed and 13 people including six members of the al-Mahdi Army were injured in the clashes, an al-Sadr spokesman said.
Earlier, an AFP correspondent reported witnessing US occupation troops surrounding the home of al-Sadr.
US armoured vehicles, backed by Iraqi security forces, cordoned off the Al-Zahra neighbourhood, where al-Sadr's home is located in the eastern part of the city, AFP said.
Smoke was seen rising from the area amid the sound of heavy gunfire, mortar fire and rocket-propelled grenade explosions.