The curfew on Tuesday came a day after at least seven people were killed in the worst anti-US riots since foreign forces overthrew the Taliban government in 2001.
Earlier in the day there were two Afghan army tanks on the road leading to the city centre from the site where the riots broke out on Monday after a US forces vehicle was involved in a fatal crash.
US forces were co-ordinating closely with the Afghan authorities, but were less in evidence in the city.
Major Luke Knittig, a spokesman for the International Security Assistance Force, said on Tuesday: "We are patrolling, but we are adopting a lower profile at the request of the government."
The unrest in the capital started on Monday when a US soldier lost control of his truck and smashed into a dozen vehicles, killing at least five Afghans.
Residents stoned the convoy the truck was travelling in, prompting at soldiers to fire warning shots, according to the US military.
A nursery school was set alight
by mobs in Kabul on Monday
The situation deteriorated further as Afghan police also opened fire to help the convoy.
There was rioting and looting in the city centre, cars were set on fire, windows smashed, and the offices of international aid groups ransacked.
An Afghan health ministry official said at least eight people were killed in the clashes.
The streets were emptier than usual on Tuesday morning.
The city's substantial expatriate community, many of them employed by aid groups, were taking particular care after much of the violence appeared directed at them.
Protesters on Monday vilified the US, marching through the streets of the city to the gates of the National Assembly and US embassy. Hamid Karzai, the Afghan president, was also criticised.
Karzai, in a televised address to the nation, called the rioters "opportunists and agitators" who could not be allowed to destroy a country still trying to emerge from conflict that has gripped it since 1979.
The violence showed the fragility
of the security situation in Kabul
Karzai won an election in late 2004, winning more than 50% of the vote, but he has been unable to shake off the perception that he owes his position to US backing.
Fighting in the south and east, where the Taliban are gaining strength, has left 350 people dead in the past couple of weeks alone.
Karzai's critics call him the "mayor of Kabul", because of the instability in the rural provinces, but the unrest on Monday showed the fragility of the situation in the capital as well.