The 38-year-old was travelling back to his hotel in a taxi when the vehicle was struck by a stolen car as it attempted to evade the police in Brazil yesterday.
Messi took to Facebook to convey his sorrow over the incident, having befriended the Argentine Lopez when he worked in Barcelona for Sport newspaper.
"I'm sending a big, big hug to the whole of Argentina and a souvenir to Jorge 'Topo' Lopez, this victory is especially also for you, my friend. A big hug to the family and lots of encouragement," he wrote on Thursday.
The Albiceleste will face Germany in the final of the competition on Sunday at the Maracana.