The pipeline, in the town of Tlahuelilpan, 60 miles north of Mexico City, exploded after thieves drilled an illegal tap, state oil company Petroleos Mexicanos, or Pemex, sad.
At a news conference with Lopez Obrador, Hidalgo State Governor Omar Fayad said 66 people were killed and 76 people injured in Friday evening's explosion, which happened as local residents tried to fill buckets and drums with fuel.
"I urge the entire population not to be complicit in fuel theft", Mr Fayad wrote on Twitter.
Mexico is regularly rocked by deadly explosions at illegal pipeline taps, a risky but lucrative business whose players include powerful drug cartels and corrupt Pemex insiders. Mexico's top federal prosecutor Alejandro Gertz said the pipeline was tapped deliberately, but that the investigation was complicated because everyone right at the blast site died.
Residents in the immediate vicinity of the pipeline, which runs from the cities of Tuxpan to Tula, have been evacuated, Pemex said.
"We are going to eradicate that which not only causes material damages, it is not only what the nation loses by this illegal trade, this black market of fuel, but the risk, the danger, the loss of human lives", he said.
The explosion is likely to further intensify efforts to crackdown on the illegal taps and focus attention on Lopez Obrador's fight against the $3.98 billion Cdn per-year illegal fuel theft industry.
Mexico has suffered from widespread fuel theft for many years, which the government claims costs the country more than $3billion.
TLAHUELILPAN, MEXICO A burnt body is observed following an explosion in Mexico.
It is believed the blast occurred after the line was ruptured by suspected oil thieves in the town of Tlahuelilpan, in Hidalgo state.
"I call on the whole government to assist people there".
The president, who took office on December 1, has vowed to keep up the fight and asked Mexicans to be patient.
His administration also shut down pipelines to detect and deter illegal taps, relying more on delivering fuel by tanker truck.
The explosion comes as gas stations in several Mexican states and the country's capital have been running dry for almost two weeks. "What happened in Tlahuelilpan today should not happen again".