Children are particularly at risk from the aftermath of bombardments in Lebanon, Israel and Gaza, the UN children's fund said.
It said it was so concerned about the danger that it was mounting an advertising campaign to warn parents to keep their children away from shiny, strange objects in the rubble.
Unicef spokeswoman, Wivina Belmonte, said on Wednesday: "We are starting to do TV and radio spots as of today, handing out leaflets to people who are crossing the border from Syria into Lebanon going back into areas that have been bombed and shelled, where there are pieces of debris that are still of great danger to people."
A similar campaign is under way in Gaza. Unicef does not have a country programme in Israel, but has a national committee that coordinates with the Israeli government to protect children's interests.
Arabic-language leaflets handed out in Lebanon read: "This war has left thousands of unexploded ordnance and cluster bombs. For your safety and the safety of your children you have to know that in all the places that have been bombarded there may be strange objects or cluster bombs of different shapes, colours and sizes.
"Be aware, be careful, don't get close to them, don't touch because they can explode and kill. If you see something strange-looking, report it to the nearest Lebanese army or the internal security forces, or call the national de-mining office."
The death of a child in south Lebanon on Monday underscored the danger of unexploded ordnance - the shells, bombs and land mines that failed to go off during the combat, but which can easily be triggered by a slight movement, Unicef and other officials said.
"We are starting to do TV and radio spots as of today"
Michael Bociurkiw, another Unicef spokesman, said: "In July alone, 38 kids have been killed [in Gaza]. This has almost been the highest number since the beginning of the intifada."
Bociurkiw, who has spent the past three years in Gaza, said the Unicef office there had stepped up warnings in recent months as the death toll among children has risen since April amid the growing Hamas-Israeli tensions.
"We feel that kids have been living in an extraordinary environment of fear and violence and insecurity.
"Kids are typically exposed to violence, for example shelling, gunfire and UXO (unexploded ordnance) when they go to and from school. Many times schools are also hit during the school year."
He said the agency was concerned about "invisible injuries" - the trauma inflicted on children - and is counselling them, their parents and other care givers.
Bociurkiw said that, while the needs in Lebanon were great, the agency feared that the attention given to Israel's northern neighbour might take attention away from the needs of Gaza.