The pledge by EU foreign policy chief Javier Solana followed talks on Thursday in which Israeli Prime Minister Ariel Sharon warned him there would be little chance of EU involvement in ending the conflict without a drastic change in the European position.
Ties between Israel and the EU have hit a new low after the 25-nation bloc voted for a Palestinian-sponsored General Assembly resolution demanding Israel heed a World Court ruling calling on it to tear down the barrier.
Solana has said the EU supported Israel's right to defend itself, but opposed the barrier because it cuts into occupied territory.
Palestinian homes have been
destroyed along barrier's route
The barrier-towering eight metres in some parts-cuts off some of the most water-rich and fertile sectors of the West Bank. It separates villages and prevents thousands of farmers from reaching their land.
Palestinians fear the razor-tipped wire and concrete wall is a land grab in exchange for the Gaza Strip and will demarcate the borders of a future state. Israel claims that the wall is necessary to keep out resistance fighters, a stance not recognised by international and human rights groups.
After failing to resolve the row in meetings with Israeli leaders, Solana wrapped up his visit telling reporters: "Europe ... is a very important international power and is going to play a role, (whether) you like it or not."
He said the EU had a right to participate because of its important interests in the region.
"The Palestinians cannot imagine a peace process without the full participation of the EU. Europe has contributed enormously since the beginning," cabinet minister Saib Uraiqat said.
Israel's relations with the EU have been strained over what it claims is favouritism towards the Palestinians in their conflict.
But Palestinians have always insisted on a European role, seeing them as more balanced to their cause than Washington, Israel's staunchest ally.
The EU, together with the United States, Russia and the United Nations, comprise a Quartet of mediators sponsoring a "road map" aimed at ending the Palestinian-Israeli conflict.