JERUSALEM — Israel retaliated for Palestinian rocket attacks on Tel Aviv and Jerusalem with five airstrikes before dawn on Saturday on the Gaza City offices of Ismail Haniya, the prime minister of Hamas — the militant Islamist group that governs Gaza.

Mr. Haniya’s office was destroyed, witnesses said, and the main police complex nearby was also hit. About the same time at the south end of the Gaza Strip, heavy Israeli bombardment was reported on the smuggling tunnels leading to Egypt. There were no reports of deaths from those strikes as of 7 a.m. Saturday, but Mr. Haniya’s office is in a populated area, and several homes around it were damaged.

The Israeli military confirmed the attacks and said it had also targeted the Hamas Ministry of Interior, a Hamas training facility, buildings where weapons were stored, and rocket launching sites. The Israel Defense Forces said it would “continue targeting sites that are used to carry out terror attacks against Israeli citizens.”

On Friday, emboldened by displays of Egyptian solidarity and undeterred by Israel’s advanced aerial firepower, Palestinian militants under siege in Gaza broadened their rocket targets, aiming at Jerusalem for the first time, sending a second volley screeching toward Tel Aviv and pushing the Israelis closer to a ground invasion.