Conspiracy theory. No evidence is provided to support the claim.
This is part of a disinformation narrative about US-led regime change operations against left-wing governments in Latin America. You can see other examples of this narrative in the EUvsdisinfo database, such as the alleged presence of a US marine in the Venezuelan barricades and the promotion of a Ukraine-style 'colour revolution', the training of Venezuelan exiles in Guyana for military operations inside the country, preparations for a military intervention after forcing Brazil to join NATO, deliberate blackouts in South America caused by the US, or the existence of plans for the secession of oil-rich regions in both Venezuela and Mexico.
This narrative also falls within the broader pro-Kremlin disinformation efforts attempting to deny the existence of genuine grass-root protests, portraying them as foreign-led efforts and fake colour revolutions.
Read the statement from the EU's High Representative/Vice President Federica Mogherini on the situation in Bolivia here.