Some rights groups say images from the conflict prove the illegal use of phosphorus
Israel insists its use of white phosphorus shells during its three-week campaign in Gaza was not illegal.
Foreign ministry spokesman Ygal Palmor said an internal investigation so far had found no evidence to support claims it was illegally fired near civilians.
White phosphorus is legal for making smokescreens in open battleground. But rights groups and journalists say it was used in crowded civilian areas.
The weapon sticks to human skin and will burn through to the bone.
It can cause death or leave survivors with painful wounds which are slow to heal. Its ingestion or inhalation can also be fatal.
The UN said its headquarters were hit by three white phosphorus shells during the offensive, causing a fire destroying much of its aid supplies.
Amnesty International, Human Rights Watch and foreign journalists who have gone into Gaza since the operation ended say they have found evidence of its use in crowded residential areas.
The Israeli army said on Wednesday it would investigate the allegations.
But Mr Palmor told the BBC that the probe had so far found no evidence to support the claims.
"Parts of the Gaza Strip are open battlefield and I'm not going to go into the specific circumstances of each and every incident because I haven't investigated and neither have you," he said.