Physicians for Human Rights-Israel (PHR) described alleged incidents which "reveal that not only did the (military) not evacuate besieged and wounded families, it also prevented Palestinian (medical) teams from reaching the wounded".
PHR's report followed accusations by other human rights groups and Palestinians that Israel's actions during the 22-day offensive in the Palestinian coastal enclave, controlled by the Islamist Hamas group, warranted war crimes investigations.
The Israeli military said the High Court had dismissed a petition PHR lodged on January 19, a day after the offensive ended, and that the allegations were still being investigated.
"At the conclusion of the fighting, the claims were investigated by the (military) in a thorough manner, as were many other issues, in the framework of an expert investigation," the military said in a statement.
"The findings ... have not yet been concluded. When they have been finalised, (they) will be presented to the public."
PHR quoted figures issued by the World Health Organisation which showed 16 Palestinian medical personnel were killed by Israeli fire during the offensive and that 25 were wounded while performing their duties.
It said Israeli forces attacked 34 medical care facilities, including eight hospitals.
PHR described incidents in which it alleged that Israeli forces "did not allow the evacuation of injured civilians who were besieged for days at a time and left the civilians without food or water for considerable periods".
In its conclusion, PHR said "on the basis of earlier reports published by PHR-Israel, a dangerous and retrograde trend can be identified of an increasing disregard for the obligation to protect medical personnel during (Israeli) operations".
The Israeli military said its forces were instructed to "act with the utmost caution in order not to cause harm to medical vehicles and medical facilities".
It said Hamas fighters had "methodically made use of medical vehicles, facilities and uniforms in order to conceal and camouflage terrorist activity, and in general used ambulances to carry terror activists and weapons".
Last week, Gaza war veterans gave accounts in the Israeli media of the killing of civilians and alleged that there was deep contempt for Palestinians among the ranks.
Defense Minister Ehud Barak responded to those accusations by repeating Israel's description of its forces as the most moral in the world. The military said its judge advocate-general had ordered an investigation of the alleged incidents.
The Palestinian Center for Human Rights has put the Palestinian death toll during the offensive at 1,434 - 960 civilians, 235 fighters and 239 police. Israeli officials have disputed the figures. Thirteen Israelis were killed.