U.S. President Barack Obama says he used a private meeting with French President Nicolas Sarkozy earlier this month to express “significant disappointment” with a French vote in favor of Palestinians joining the U.N. cultural heritage agency, UNESCO.

Mr. Obama's private November 3 meeting with Mr. Sarkozy ahead of a Group of 20 summit in the French city of Cannes made international headlines after Elysee staff accidentally transmitted part of the leaders' conversation to a group of reporters in another room.

As the reporters listened to simultaneous translation of that conversation, they heard Mr. Sarkozy criticize Israeli Prime Minister Benjamin Netanyahu as a “liar” whom he “cannot bear.” With both leaders unaware that their microphones had been turned on, Mr. Obama appeared to sympathize with Mr. Sarkozy, saying “You may be sick” of Mr. Netanyahu, but “I have to work with him every day.”

Asked about those remarks at a news conference in Honolulu late Sunday, Mr. Obama said he would not comment on that part of the conversation. But, he said the main point he made to the French president was his disappointment that France voted for the Palestinian Authority to join UNESCO on October 31 despite knowing that such a move would force Washington to cut funding to the agency.

UNESCO members overwhelmingly approved the membership bid by Palestinians, with Israel, the United States and several of their allies voting against. U.S. laws bar the government from funding any U.N. agency that admits Palestinians as a full member.

Mr. Obama said he made the argument to Mr. Sarkozy that the only way to resolve the Israeli-Palestinian conflict and create a Palestinian state is for both sides to “sit down at the table and negotiate.” He said Palestinian efforts to bypass that process by seeking recognition of statehood through the United Nations will not work.

In another development, Israeli aircraft attacked a Hamas militant security post in the northern Gaza Strip late Sunday, killing one Hamas security officer and wounding four others. The Israeli military said it was responding to a rocket attack from Gaza into southern Israel earlier in the day. The rocket caused no damage or casualties.

It was not immediately clear which Palestinian militant group fired the rocket. Israel has said it holds Gaza's Hamas rulers responsible for all attacks emanating from the territory. A series of Israeli air strikes on Gaza and Palestinian rocket attacks on southern Israel killed at least 10 militants and one Israeli civilian late last month.