The vehicles were targeted in the Derrybeg area around midnight on Sunday.
Sinn Fein MLA Liz Kimmins said the incident has left the “close-knit community” in “total shock” on Monday, stressing it was fortunate no one had been injured in the attack.
“I condemn last night’s arson attack which saw a number of cars burned, including that of a heavily pregnant woman, which has caused her and her husband huge stress,” said the Newry and Armagh representative.
“My colleague, councillor Charlie Casey, and I have spoken with a couple who had their car and work van burned in this incident and were extremely shook up.”