Demonstrators called on Moldova's political leaders to amend the constitution to specifically mention the country's European orientation.
"I believe in a European Moldova and want for my country a future with advanced economic and socio-political development," said 18-year-old attendee Alexandrina Miron.
"Right now we are a little behind, but we will slowly catch up and stand on par with Europe."
The leader of the pro-Russian opposition Shor party, exiled businessman Ilan Shor, told his supporters at rival protests in several cities via video link that he would seek a referendum on Moldova's foreign policy.
Shor, sanctioned by the U.S. as an agent of Russian influence in Moldova, was handed a 15-year jail sentence in absentia last month for his role in the 2014 theft of $1 billion from Moldovan banks.
