Air strikes are reported to have hit the Yemeni capital, Sanaa, and the port city of Hudaydah on the Red Sea.
The scale of the strikes or any casualties are not clear from initial reports.
In recent days Israel has warned it was preparing a significant attack on Houthi rebel targets in Yemen after the group fired missiles at it.
Houthis have been attacking Israel with drones and missiles since the first months of the Gaza war, which began in October 2023. The war was triggered by an unprecedented attack on Israel by Hamas gunman from Gaza, which was praised by the Houthis.
Israel has carried out intermittent strikes against Houthis in retaliation since then.
