Erekat, speaking on Army Radio Monday, said Palestinians need to hear that agreement from Israeli Prime Minister Binyamin Netanyahu.
"Until we hear that, I think it would be a waste of time to speak about any other issue," the Palestinian negotiator said. "If Netanyahu thinks that 1967 lines are an illusion, then peace for him is an illusion."
Using the1967 lines as a basis in talks refers to Israel's borders as they were before a war that led to the occupation of the West Bank and Gaza.
Other issues that need to be resolved are the status of Jerusalem and the return of Palestinian refugees, Erekat said.
On Sunday, U.S. President Barack Obama, addressing the American Israel Public Affairs Committee, said the 1967 lines would have to be adjusted to take into account new demographic realities and address Israel's security concerns.
"I am a partner with the president's desire to advance peace and I appreciate his efforts in the past and the present to achieve this goal. I am determined together with President Obama to find ways to renew peace negotiations," Netanyahu said in a statement reported by The Jerusalem Post.
"Peace is a vital interest for us all," the statement concluded.
Hamas spokesman Sami Abu Zuhri slammed Obama's speech Sunday. He said the American president's demands that Hamas recognize Israel and renounce violence will go unanswered, Ma'an news agency said.
The U.S. administration is not a "friend to the people of the region," the agency quoted him as saying. "The U.S. administration will fail, just as all others have in the past, in forcing Hamas to recognize the occupation.