De Villepin questioned on Wednesday whether the barrier would boost security or whether on the contrary it risked "fuelling the hatred" between Palestinians and Israelis.
Addressing about 400 guests, Shalom replied that the barrier was "necessary and legitimate" and that there was no other way to protect the Israeli people against "terrorist attacks".
A barrier was "always reversible, human lives are irreversible," he said to applause. Shalom said that since the barrier was erected, the number of attacks had gone down in Israel and the number of victims was the lowest last month since the Palestinian intifada resumed three years ago.
To justify the building of the barrier, Shalom said Israel had been subjected to 19,000 attacks over the past three years.
De Villepin firmly condemned "terrorism" which, he said, "nothing can ever justify", but he defended the need to "take the risk of peace," saying peace was "the only guarantee of a lasting security" for Israel.
This peace could, however, be guaranteed only if Israel respects international law, by accepting an end to the occupation of the Palestinian territories, he went on.
"It is necessary to resume a cycle of negotiations, show that
the dialogue is making progress, that it can produce results unlike violence," de Villepin said.
Shalom insisted on putting into practice the road map. But he stressed that the first stage of the peace plan was the dismantling of "terrorist structures".
He said: "Ceasefires are welcome, but they are not enough," and called on the Palestinians to act.