Anouar El Okka, a Belgian doctor of Palestinian origin, is one of the 14 plaintiffs that Beauthier is representing.
Okka claims that his olive grove in Gaza was bombarded and then set of fire with phosphorous by Israeli forces.
The complaint also cites the bombing of the Ibrahim al-Maqadna mosque,near the refugee camp of Jabaliya, in which 16 civilians including children were killed.
More than 200 people were inside the mosque praying when it was struck.
The other 13 plaintiffs are all Palestinians who were wounded or lost a relative in the attack which results in about 1,400 deaths of mainly Palestinian civilians.
The 70-page complaint also refers to the conclusions of a UN-commissioned report which accused Israelis and Palestinians of war crimes in Gaza.
The plaintiffs said that they did not trust the Israeli court system, "because it is not independent, reliable, or honest according to the criteria of international law".
It is not the first time such legal action has been taken in Belgium.
In 2001, a complaint was filed against Ariel Sharon, a former prime minister, over massacres at refugee camps two decades earlier.
That legal move caused a diplomatic spat between Israel and Belgium and led Brussels to change its universal jurisdiction law, allowing it to apply only in cases that involved Belgian nationals.
Last week, Israeli media reported that Barak cancelled an official visit to Paris after French passengers of the Gaza aid flotillathreatened to file a case against him over a deadly raid that killed nine activists.
The passengers, together with three members of the French parliament, threatened to file cases against Barak both in France and in the International Criminal Court, in the Hague.