FIFA says Syria will play its home leg against Tajikistan on July 23 in neutral Jordan, at a city to be chosen.
Tajikistan will host Syria in Tursunzade for the return leg five days later.
Yemen is also judged unsafe to host World Cup qualifiers during ongoing protests against President Ali Abdullah Saleh.
FIFA says it's still confirming a neutral venue for Yemen's return match against Iraq on July 28. Iraq hosts the first leg at Arbil.
The winners will advance to the main qualifying draw being conducted July 30 in Rio de Janeiro, Brazil.