Conservative President Mauricio Macri condemned the call to strike in Latin America's third-biggest economy, where he faces midterm legislative elections in October.
The strike shut down schools, banks and public transport and demonstrators blocked streets as Macri hosted international leaders and businesspeople at an economic forum.
The National Civil Aviation Administration said the strike disrupted 800 flights, affecting some 60,000 passengers. Buenos Aires Ezeiza international airport was effectively shut down.
Police and demonstrators clashed during a rally near one of the roads into Buenos Aires.
Judicial sources said five people were injured and six arrested, lowering an earlier toll of arrests.
