Demonstrators chanted calls for freedom and for long-time President Islam Karimov to step down.
The protesters demanded that the Uzbek government free political prisoners and allow exiled opposition leaders to return to Uzbekistan to participate in a presidential election tentatively slated for December.
Karimov has been silent on the topic of the election, but many observers expect him to try to skirt a constitutional clause that limits presidential service to two terms.
The demonstrators told RFE/RL's Uzbek Service that they also want EU leaders to put more pressure on Tashkent over democracy and human rights.
The protest took place as Uzbekistan prepares to mark the 16th anniversary of its independence from the Soviet Union on September 1 with gatherings and concerts in the capital, Tashkent, and elsewhere.
The government -- which has repeatedly told Western critics to stay out of its internal affairs -- has declared that the theme of this year's celebrations is "Don't Teach Us How to Walk."