A magnitude 6.0 earthquake was felt in southern Mexico and Mexico City early on Saturday, prompting people to flee into the streets two days after a similar tremor.
There were no immediate reports of damage or injuries.
The earthquake occurred at 2.36am. It was the 22nd aftershock following a magnitude 6.4 tremor on Thursday.
Mexico City is sensitive to distant earthquakes because it was built over soft soil from a drained lake that magnifies their effect.
A magnitude 7.2 earthquake shook the capital and the Pacific resort of Acapulco on 18 April.
At least 10,000 people were killed in Mexico City by a magnitude 8.1 earthquake in 1985.