The American Bar Association/Central European and Eurasian Law Initiative was found guilty of giving legal support to unregistered organisations, a pro-government Internet website, www.press-uz.info, said.
Other charges against the association included failing to submit financial documents confirming use of its assets, according to the report.
The legal association first opened its office in Tashkent, the Uzbek capital, in 1995. Representatives from the organisation declined to comment immediately on the court decision.
Another two US-funded organisations, Freedom House and the Eurasia Foundation, had to close their Uzbek offices after being found guilty of similar charges in March.
Uzbek authorities have increased control over foreign organisations and media outlets in the wake of popular uprisings in other former Soviet republics, including neighbouring Kyrgyzstan last year.
Uzbekistan has been especially sensitive about foreign scrutiny following bloody disturbances in the eastern city of Andijan in May 2005. The government blamed the violence on local Islamic insurgents, but human rights groups and witnesses said security forces massacred demonstrators.
Last year, Uzbek authorities also closed down the offices of Internews, a US-based media support group, and IREX, another US-based educational group.