The epicentre of the quake was reportedly located at a depth of 57 km, seismologists said. No injuries or damage have yet been reported.
A 5.3-magnitude quake has hit 34 km south of Playa Los Cobanos and 73 km southwest of San Salvador, according to the European Mediterranean Seismological Centre.
The earthquake occurred at 2:13 a.m. local time.
Seismological centres across the world reported the magnitude of the quake ranged from 4.7 to 5.5 on the Richter scale.
There have so far been no reports of potential injuries or significant damage.