Ismail Ziada, a Dutch-Palestinian man, lost his mother, three brothers, a sister-in-law, a young nephew and a friend in the strike during Israel's Operation Protective Edge targeting Gaza.

Gantz, who is now the main political rival of Prime Minister Benjamin Netanyahu, was the chief of general staff of the Israeli defence force (IDF) at the time of the airstrike on the Bureij refugee camp in Gaza on July 20, 2014.

But The Hague district court said that under international law it could not hear the case, which named Gantz and former Israeli air force chief Amir Eshel.

"The district court has ruled that the Dutch court is not competent to hear the case, because the former Israeli officials have functional immunity from jurisdiction," Judge Larisa Alwin said.

"This form of immunity, a legal concept in customary international law derived from state immunity, applies to acts carried out in the performance of a public duty," she said.

"The air strike in the Gaza Strip, in which six of the claimant's relatives were killed, is an example of an act carried out in the performance of a public duty."

- 'Horrendous crime' -

Israel said it launched Protective Edge at the time to stop rocket fire against its citizens and destroy tunnels used for smuggling weapons and militants.

Ziada said he intended to appeal against Wednesday's ruling.

"My feeling is deep sorrow and disappointment," Ziada told reporters outside the court.

"I am a Dutch citizen who has been a victim of a horrendous crime and here a Dutch court says I have no access to justice."

Thom Dieben, lawyer for the defendants, said they were "pleased with the outcome."

"The reasoning is legally sound and in line with international law and that was what this case was all about," he told reporters.

"This case does not belong in a Dutch court, it belongs in an Israeli court. That was the line put forward by the IDF officials and that's what in our view the court has now accepted."

At a hearing in September Ziada told judges he was "seeking justice" and would not get a fair hearing before an Israeli court.

"The claimant believes that he cannot file his claim anywhere else and that the case has sufficient ties with the Netherlands, because he holds Dutch nationality and lives in the Netherlands," the court said.

Operation Protective Edge left 2,251 dead on the Palestinian side, most of them civilians, and 74 on the Israeli side, most of them soldiers.