BERLIN — French President Francois Hollande has made contact with the leaders of Israel and Egypt to try to prevent an escalation of fighting in the Gaza Strip, Prime Minister Jean-Francois Ayrault said on Thursday.

The killing of a Hamas militant commander in an Israeli airstrike on Wednesday has sparked a wave of reciprocal attacks between Israel and the Islamist Hamas, which rules Gaza. A total of 16 Palestinians and three Israelis have been killed.

"It's time to stop this escalation, which is dangerous for the security of Israel and its people and for that of the Palestinian people," Ayrault told reporters during a visit to Berlin.

France had made "direct contact" with Israeli Prime Minister Benjamin Netanyahu and Egyptian President Mohamned Morsi, he added. "France will do everything it can to avoid an escalation of the violence."

Morsi on Thursday condemned Israeli air strikes on Gaza as unacceptable aggression and ordered Egypt's prime minister to visit the neighbouring enclave in a show of support for the Palestinians.

Two rockets fired from Gaza on Thursday targeted Tel Aviv in the first attack on Israel's commercial capital in 20 years, raising the stakes in the showdown between Israel and Palestinian militants. No casualties or damage were reported.

Israeli warplanes bombed targets in and around Gaza city for a second day, shaking tall buildings. In a sign of possible escalation, Israel's armed forces spokesman said it had received the green light to call in up to 30,000 reserve troops.