The president accused his Venezuelan counterpart of "imposing suffering on his people."
"The situation in which Venezuelans live is dramatic. I want to condemn the repression deployed by Maduro and his actions to prevent the Venezuelan people from receiving humanitarian aid," Macri tweeted Saturday at around midnight.
"Once again I renew Argentina's support of the President-in-Charge Juan Guaidó and the efforts of the National Assembly to get the food and medicines so necessary to alleviate the suffering that Maduro has imposed on its own people," he added in another tweet.
The Foreign Ministry, in a statement, also condemned "vigorously the actions of the Maduro regime that have prevented the entry of humanitarian aid from neighbouring countries, designed to alleviate the dramatic situation" Venezuelans are facing.
"The Argentine government firmly repudiates the repression deployed by the regime's forces, which caused several deaths and dozens of wounded," the ministry added.
Two people were killed and hundreds wounded as Guaidó supporters clashed with Venezuelan security forces on Saturday in a failed attempt to cross in truckloads of humanitarian aid from Colombia and Brazil.
The European Union condemned Venezuela's use of violence and armed civilians to block the aid entry, while United Nations Secretary-General Antônio Guterres said he was "shocked and saddened" by the civilian deaths.
Guaidó flew to the Colombian capital of Bogotá on Sunday for the meeting with members of the Lima Group – 13 Latin American countries plus Canada that are seeking to resolve Venezuela's political impasse. The group plan to hammer out a strategy to remove his rival Nicolas Maduro from office.
Guaidó, the 35-year-old leader of Venezuela's National Assembly, declared himself acting president in January after the opposition controlled legislature concluded that Maduro was fraudulently re-elected. Some 50 countries recognise him as Venezuela's legitimate president.
"Today we consolidated yesterday's victory, tomorrow we'll consolidate it even more," Maduro's right-hand man Diosdado Cabello said Sunday at a pro-government rally in the border town of Tachira. "Not a single one of those trucks with aid got through."
Maduro seems to have won this round in the power struggle, even though over 150 members of Venezuela's security forces have deserted to Colombia or Brazil.
A 14-year-old boy was among those killed Saturday near the Brazilian border in clashes with Venezuelan security forces. More than 300 people were injured in a day of disturbances at crossings on the Colombian and Brazilian borders.
Sporadic clashes between hooded protesters and police, supported by terror-spreading armed civilian "colectivos," continued Sunday on the Venezuelan side of the border, but were not as intense as the day before.
Scores of Venezuelans who managed to slip across the border to get aid were trapped there as Venezuelan authorities had closed the border.
Nicolása Gil, a frail 71 year-old who spent the night in Cucuta near one of the crossing points, said she was "scared to cross into my country.
"Here we're safer than over there," she told AFP.
The attempt to cross aid stockpiled in Colombia led Maduro to sever ties with Bogotá – and on Sunday, a group of Colombian diplomats trickled across one of the border bridges on foot, luggage in tow.
Also Sunday three Bolivarian National Guard sergeants fled Venezuela and sought refuge in Brazil.
In the barracks "there is no food," said one of the defectors, identified as Carlos Eduardo Zapata.
"They don't even have mattresses. Us National Guard sergeants are sleeping on the ground."