Thousands of extra border guards and police officers were deployed in "sensitive sectors", notably in schools, commercial centers and shopping malls as Israel prepared to celebrate a holiday weekend, a police spokesman in Tel Aviv said.

Roadblocks had also been set up on roads in major cities.

The heightened security comes after Hamas vowed to avenge the deaths of three of its members who were killed in an Israeli air strike near Gaza City on Wednesday.

Israelis are celebrating the Jewish festival of Purim this weekend, with carnivals throughout the country, where police are expected to be out in force.

Military chief of staff Moshe Yaalon announced Tuesday that the army would intensify its operations against Palestinian militants "in the light of the intensification of the activities of the terrorist organisations over the last few weeks".

The car was targeted with two rockets close to the Jewish settlement of Netzarim, which lies just south of Gaza City, witnesses said. Medical sources at Gaza's Al-Shifa hospital said two passers-by were injured in the attack.