Security fears in the Gulf region led to a spike in the oil price after air strikes on Yemen provoked Iran to demand a halt to “aggressions”.
Yemen has also closed its seaports.
Saudi Arabia is leading the offensive involving Gulf state forces against Houthi rebels who have taken the capital and assumed power.
Yemen sits on a 40-kilometre wide entry point to the Red Sea and the Suez canal beyond, the major shipping route between Europe and the East.
Iran says it will “make all necessary efforts to control the crisis in Yemen.”