Leaders of the trade federation say President Mauricio Macri will not win over investors by threatening their status, cutting wages and reducing the standard of living.
Argentina's main labour unions took to the streets of the capital on Tuesday demanding more jobs and protesting centre-right President Mauricio Macri's economic policies.
Tens of thousands of workers gathered in the historic Plaza de Mayo, criticising Macri, who is trying to lower labour costs to attract investment and jump-start an economy that emerged from recession in the second half of last year.
"If some retrograde [in the government] thinks that lowering wages, precarious living conditions and destroying trade unions is going to line up investments ... we say that is very wrong," said Juan Carlos Schmid, a leader of Argentina's largest umbrella union, the CGT.
Standing on a podium at the protest, he said the CGT would meet in late September to discuss a potential strike.
Macri told Reuters in an interview this month his government was negotiating labour agreements sector by sector rather than trying to pass a comprehensive labour reform like the one approved in neighbouring Brazil.
Unions fear more drastic changes could be coming after mid-term legislative elections in October, however, especially after a primary vote on August 13 pointed to strong support for Macri's coalition.
Macri is trying to open Argentina's long protected economy and focus on competitive industries like oil and agriculture, but has seen some manufacturing jobs lost in the meantime.
The most recent employment data showed the jobless rate rose to 9.2 percent in the first quarter of the year from 7.6 percent in the fourth quarter of last year.
Some of the protesters on Tuesday were carrying posters of an activist who went missing earlier this month.
Human rights groups have said the activist was supporting the Mapuche indigenous group in Argentina and was "forcibly disappeared" by military police.
Santiago Maldonado, 27, was detained by state forces after joining in a Mapuche protest, according to campaign groups including the Grandmothers of the Plaza de Mayo.
The Grandmothers have campaigned for decades for the victims of the country's 1976-1983 dictatorship. Ex-military leaders from that era have been convicted of deaths and disappearances under the regime.
He is said to have last been seen being put into a military police vehicle by officers who broke up a demonstration in the southern province of Chubut. The demonstrators had been demanding the release of a jailed Mapuche leader.
Maldonado had moved from the Buenos Aires area to Chubut last year.
The Mapuche are considered the earliest inhabitants of parts of Argentina and Chile.
Their numbers were reduced after the Spanish conquest and subsequent independence of the countries. They have since pursued historical claims against the authorities for territory and rights.
A small Mapuche community in Chubut is claiming territory in an area of land bought by Italian fashion magnate Luciano Benetton.