The EU has accused Israel of using "disproportionate" force and making a humanitarian crisis worse during operations in the Gaza Strip.
Israeli troops have been moving deeper into Gaza
On Friday Israel consolidated its hold on northern Gaza, as air strikes killed at least three Palestinian militants.
It followed the worst day of violence since Israeli forces entered Gaza over a captured Israeli soldier - 22 Palestinians and an Israeli died.
Israel's operations are the biggest since it withdrew from Gaza last year.
"The EU condemns the loss of lives caused by disproportionate use of force by the Israeli Defence Forces and the humanitarian crisis it has aggravated," Finnish Prime Minister Matti Vanhanen, whose country holds the EU's rotating presidency, said in a statement.
The EU is Israel's largest trading partner and rarely criticises the country in such terms military or security matters.
Meanwhile an Israeli minister suggested that if Corporal Gilad Shalit, captured 12 days ago, was released, Israel may be prepared to consider future prisoner releases.
A spokesman quoted Interior Minister Avi Dichter as saying that Israel "knows how to carry out a release of prisoners as a goodwill gesture".
Until now Israel has said it will not negotiate a prisoner swap, originally suggested by Islamic militants Hamas as a solution to the crisis.
Earlier Palestinian Prime Minister Ismail Haniya called for international intervention to stop the Israeli offensive.
Mr Haniya, who belongs to Hamas, called it a "crime against humanity".
He said the Israeli push was "a desperate effort to undermine the Palestinian government under the pretext of a search for the missing soldier".
The interior minister in the Hamas-led government, Said Siyam, has urged all the administration's security forces to fight Israeli troops.
In a statement read out by his spokesman, Khalid Abu Hilal, he called on them to do their duty by "resisting this treacherous invasion and aggression of the cowardly Zionists".
In other developments:
- A Palestinian militant was shot dead in clashes with Israeli troops in a refugee camp near the West Bank town of Nablus
- At least one Palestinian teenager died as a result of Israeli fire following an incursion in Jenin, reports say
- In the last few days Israeli police have arrested 749 Palestinians they say were living in Israel illegally, as well as several Israelis said to be employing them
Many of those killed in the air strikes and heavy fighting in northern Gaza are militants but there are also civilian victims.
The Israeli military says more than 40 militants have died since the offensive started last week.
Friday morning's air strikes targeted armed Palestinians, it said.
One Hamas militant was killed and three others were wounded when Israeli forces opened fire on them from an aircraft in the early morning, Hamas and hospital officials said.
Later two militants were killed in a missile strike.
The Israeli offensive began largely in southern Gaza in an attempt to free Cpl Gilad Shalit, after he was captured by militants on 25 June.
But troops moved deeper into the north of the territory after rocket attacks on the nearby Israeli city of Ashkelon.
In New York, the UN Security Council has debated a draft resolution demanding an immediate Israeli withdrawal from Gaza and the release of detained Palestinian officials.
The draft was presented by Qatar on behalf of the UN's Arab Group, but appears doomed in view of opposition from the US, which has the power of veto.
The draft does not mention the Palestinian rocket attacks or Cpl Shalit's capture, and the US ambassador to the UN, John Bolton, said the document was "not balanced".