The pipelines have since been reopened and security stepped up.
The market for stolen fuel has also unleashed a turf war between rival gangs, similar to that seen between drug cartels.
Salamanca is less than 100 kilometers (60 miles) from Santa Rosa de Lima, where authorities have carried out a days-long operation against Juan Antonio Yepez, the alleged leader of a fuel-stealing cartel.
In late January, a fake bomb was found in a car parked close to the Salamanca refinery.
Nearby, a sign was posted with a threatening message for Lopez Obrador and a demand that security forces be withdrawn from the state. The sign was believed to be Yepez's handiwork.
The leftist Lopez Obrador, 65, took office on December 1.
The anti-establishment austerity crusader famously disbanded the presidential guard when he took office. Security analysts have warned his safety could be at risk.
Some now say the violence associated with fuel theft is as serious as that stemming from the drug trade.
More than 200,000 people have been murdered in Mexico since 2006, when the government controversially deployed the army to fight drug trafficking.
Mexico registered more than 33,000 homicides last year, the most since national record-keeping began in 1997, according to government figures.