Abbas was replying to Prime Minister Binyamin Netanyahu, who said the only path to peace is negotiations. The threat of unilateral action indicates the depth of the crisis over peace talks restarted just last month by US President Barack Obama.
Israeli settlements in the West Bank are at the heart of the current stalemate. Netanyahu imposed a 10-month halt to new construction in settlements last November to bring Palestinians back to the table. But it took nine months of intensive US mediation to restart direct talks.
Netanyahu faced stiff opposition to the building restrictions from inside his government and said he would not renew the measure, which expired Sept. 26. Construction has begun on more than 500 new homes since then, according to settler officials and a count by The Associated Press.
Palestinians insist they will not hold talks while settlement construction continues. They have been suggesting recently that they would seek other solutions if the talks fail.
One possibility would be asking the United Nations to recognize a Palestinian state in the West Bank, Gaza Strip and east Jerusalem, territories Israel captured in the 1967 Mideast war.
That would not dislodge the Israeli military from the West Bank, dismantle the 120 Jewish settlements there or give Palestinians free access to east Jerusalem. But it could isolate Israel and change the diplomatic equation.
On Sunday, Netanyahu criticized this idea.
"I think any attempt to circumvent it by going to international bodies isn't realistic and won't advance true peacemaking in any way," Netanyahu said. "Peace will be achieved only through direct talks."
During a visit to Bethlehem on Monday, Abbas responded that Israel has been taking unilateral measures in the West Bank for decades — especially by building settlements.
"Settlements are a unilateral step done by Israel," Abbas said. "Is there anything clearer than settlements and invasions and roadblocks and all that has been done on Palestinian land?"
Given that reality, Abbas said, Netanyahu should not lecture the Palestinians about a step they might take in the future, "which is to resort to the United Nations."
Palestinian officials have mentioned this possibility before, but Abbas' statement was a rare on-the-record reference to the idea.