Foreign Minister Shimon Peres, who shares the award with Rabin and PLO chief Yasser Arafat, called the process "irreversible.''
Rabin and Peres spoke at a news conference after arriving in Oslo for Saturday's pomp-filled ceremony at city hall.
Arafat arrived at Oslo's Fornebu airport later Friday. He was expected to attend a dinner and have talks with Peres and Rabin during the evening.
At the airport, Arafat said the prize made for a happy day for himself personally and for all the Palestinian people.
Israelis and Palestinians hope the same "spirit of Oslo'' that brought the two sides together in last year's peace agreement may help them overcome remaining hurdles.
But despite the hopeful words, reminders of the lingering troubles remain.
About 50 demonstrators protested outside the hotel where Rabin and Peres were speaking, to show opposition to Arafat's sharing in the award after years of PLO-sponsored terrorism.
One protester's sign said "Arafat's hand dripping in blood accepts the Nobel Prize.'' Yet, Rabin sees things differently, and defended Arafat from accusations of murder.
"The receiving of the Nobel Prize will serve as encouragement to continue with our efforts to solve the problems,'' he told the news conference.
Rabin said that Israel remains "committed'' to letting the Palestinians hold elections and to the redeployment of Israeli troops in the West Bank, as provided in the peace accord.
"The peace process is not yet completed but it is irreversible. What was been done already exceeds most of our expectations,'' Peres said.
Protesters have flown in from around the world to heckle the laureates.
Before Rabin and Peres reached the Norwegian Nobel Institute to meet the awards committee, about a dozen police officers arrested New York Rabbi Avi Weiss and three other protesters amid shouts of "shame, shame'' by a small crowd outside the building.
Bjorn Jorgensen of the Oslo police said the protesters were arrested because they refused to stay in a zone set aside for their demonstration. Weiss had been leading a series of protests in Oslo.
"We feel it's an obscenity,'' said Dov Hikind, a New York state assemblyman who had flown to Oslo to protest the prize.
"Fifteen months after the signing of the peace there is more killing, more terrorism taking place in Israel, more Jews having been killed than in any period prior to that,'' said the lawmaker, who was not arrested.
Despite the hostile tone of protesters, there is still some hope that Oslo can do again what it did for Israelis and Palestinians last year.
Rabin, Peres and Arafat will meet over the weekend -- between Friday's news conferences, Saturday's awards ceremony and Sunday's receptions -- to try to resolve some of the problems that for months delayed expanding self-rule to the West Bank.
A key hurdle is the Israeli troop pullout from Palestinian towns in the West Bank, stipulated by the accord to be held on the eve of Palestinian elections. Israel is in favor of holding elections to help shore up Arafat's rule, but is in no rush to redeploy troops, citing the rash of attacks on Israelis by Muslim militant opponents of reconciliation.
Ninety-four Israeli civilians and soldiers have been killed since the September 1993 signing of the Gaza-Jericho agreement.
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