Thaçi was a leader in the war of independence against Serbia, but the tribunal in the Netherlands sentenced him to 25 years in prison for war crimes.
Three other leaders of the Kosovo war against Serbia were also sentenced to long prison terms. The war claimed around 13,000 lives and was only ended by NATO bombing of Serbian targets.
Many of those who protested against the verdict in nine cities on Friday carried flags in the colors symbolizing the Kosovo Liberation Army (KLA) movement - blood red, black and gold.
"(The verdict) is a stain on our nation's history," said Bajram Shala, who was a member of the KLA.
