The chief target of Wednesday's peaceful protest was the U.S. Embassy.
Coca is a mild stimulant of high religious and social value in the Andes. It fights hunger and alleviates altitude sickness. But it is also the raw material of cocaine.
Washington last week formally objected to Bolivia's proposal to remove a prohibition on coca chewing from the international Single Convention on Narcotic Drugs.
Bolivia's U.N. Ambassador Pablo Solon says that Bolivia does not seek to remove coca from a list of controlled substances.