The demonstrators, who plan to camp for 48 hours in the heart of the city, say rampant inflation has left many of the poorest Argentinians struggling to buy food.
"Argentina is devastated by inaction, hunger, and poverty, and we demand answers that live up to the situation," organizer Eduardo Belliboni said. "We want social programs, we want to increase allocations for existing programs and increase food rations in schools," he added.
Clashes broke out with police as demonstrators tried to block public transport networks.
On Thursday, Argentinian lawmakers will consider a "food emergency" bill, presented by the opposition, that would allow more funds to be allocated to manage the increasingly desperate situation.