Argentine courts have blamed the attack on Iran. But no one has been brought to trial in either that case or the deadly 1992 bombing of the Israeli embassy in Buenos Aires. Iran denies playing a role in either attack.
"We know without a doubt that Iran and Hezbollah initiated and backed up the attacks," Netanyahu told reporters. Hezbollah is an Islamist militant group based in Lebanon.
Praise for Macri
He praised fellow conservative Macri for jump-starting efforts to solve the crimes. Critics accuse previous Argentine leader Cristina Fernandez of trying to improve ties with Iran rather than focusing on bringing the bombers to justice.
"He strengthened Argentina's position compared with what it was before. I honor his commitment and the integrity of his effort to determine what happened," Netanyahu said.
Under Fernandez, the prosecutor probing the attack on the AMIA Jewish community center was found dead in January 2015, just hours before he was to appear in Congress to outline his accusation that Fernandez had tried to clear the way for a "grains for oil" deal with Iran by whitewashing Iran's role in the truck bombing.
Prosecutor's death in question
The prosecutor, Alberto Nisman, was discovered on the floor of his Buenos Aires apartment with a pistol by his side and a bullet in his head. The death was classified as a suicide, but Nisma's family and friends dismissed that idea as absurd.
Opinion polls show most Argentines believe his death was a homicide.
Macri won the presidency and succeeded Fernandez in late 2015. He has since boosted ties with the United States and Israel while trying to attract the foreign investment he says is needed to stimulate an economy damaged by the inflationary policies and heavy currency controls of the Fernandez years.
Macri has met with Nisman's family and says he has made a high priority of solving his death and the AMIA bombing.
Israeli Prime Minister Benjamin Netanyahu, from left, and his wife Sara, alongside Agustin Zba, President of the Argentine Israeli Mutual Association Jewish community center, walk past a wall with names of the victims of the 1994 AMIA bombing in Buenos Aires.
Executives join Netanyahu
Netanyahu and Macri are also "in ideological harmony" on issues like free trade, development and security, Israel's ambassador to Argentina Ilan Sztulman told local radio.
Netanyahu is traveling with executives of 30 Israeli companies looking to increase trade with Latin America.
They include cyber security, irrigation and other agricultural technology firms that could help Argentina reinforce its position as the world's top exporter of soymeal livestock feed and a major supplier of corn and raw soybeans.
Visits to Colombia, Mexico, United Nations
After Argentina, Netanyahu will visit Colombia and Mexico before addressing the United Nations General Assembly on Sept. 19. The diplomatic flurry might take domestic attention off two corruption investigations centering on Netanyahu in Israel.
He was accompanied on the trip by his wife Sara Netanyahu.
On Friday, Israel's attorney general said he was considering indicting her on suspicion of using state funds for personal dining and catering services amounting to some $100,000.