US President Barack Obama said Israeli Prime Minister Benjamin Netanyahu's pre-election disavowal of a two-state solution to the Israeli-Palestinian conflict makes it "hard to find a path" toward serious negotiations to resolve the issue.
"I did indicate to him that we continue to believe that a two-state solution is the only way for the long-term security of Israel, if it wants to stay both a Jewish state and democratic," Mr Obama said.
"And I indicated to him that given his statements prior to the election, it is going to be hard to find a path where people are seriously believing that negotiations are possible."
Mr Netanyahu declared, before the election, that there would be no Palestinian state on his watch although he has since tried to backtrack from his comment.
Mr Obama said: "Well, we take him at his word when he said that it wouldn't happen during his prime ministership, and so that's why we've got to evaluate what other options are available to make sure that we don't see a chaotic situation in the region."
President Barack Obama told Benjamin Netanyahu the US would "reassess" its policy options after the Israeli prime minister took a position against Palestinian statehood during the election campaign, a White House official said.
Obama called Netanyahu to congratulate him on his election win and used the opportunity to reaffirm US commitment to a two-state solution to the Middle East conflict.
But he also delivered another message, saying the US will need to "reassess" its options following Netanyahu's comments on the two state solution, the official said.
The final tally in Israel's general election shows Prime Minister Benjamin Netanyahu's right-wing party Likud won by just five seats.
With 99.5 per cent of votes now counted, Likud claimed 29 seats in the election, while the leftist opposition - Zionist Union - won 24 of the 120-seat Knisset.
A coalition of right-wing politicians will now be formed over the coming weeks.
Israel's opposition leader has officially conceded in the country's hotly-contested general election.
Isaac Herzog, leader of the leftist Zionist Union party, said he had spoken to Prime Minister Benjamin Netanyahu and had congratulated him on the victory of his right-wing Likud party.
A few minutes ago I spoke with Prime Minister Benjamin Netanyahu and congratulated him on his achievement and wished him luck.
Despite exit polls showing the two parties as almost level, Mr Netanyahu has claimed a win and has invited other right-wing politicians to join him in a coalition government.
The final results of the Israeli election show a resounding victory for Prime Minister Benjamin Netanyahu's Likud party, the Associated Press reports.
Benjamin Netanyahu's main challenger, Isaac Herzog, has disputed the prime minister's claim of victory in Israel's election, saying, "Everything is open".
"This result allows us to return to power," Herzog told supporters at his party's headquarters in Tel Aviv.
"We will wait for the real results ... everything is open", he said.
Israeli Prime Minister Benjamin Netanyahu said he had invited other right-wing politicians to join him in a coalition government "without delay".
"Reality does not take a break," Netanyahu said in a speech to supporters after two television exit polls gave Likud a narrow lead over his centre-left challenger in the ballot.
Challenger to Prime Minister Benjamin Netanyahu, Isaac Herzog has said that "everything is open" in the election results.
He responded to Netanyahu's tweet of a "major victory" for Likud in the election.
Official results are not expected to be released until at least Wednesday morning.
Israeli Prime Minister Benjamin Netanyahu has tweeted that his party has won "a major victory for the people of Israel".
The tweet, in Hebrew, read: "Against all odds: A great victory for the Likud, a major victory for the national camp led by the Likud, a major victory for the people of Israel."
No official statement on behalf of the Israeli Prime Minister has been released.
Against all odds:a great victory for the Likud. A major victory for the people of Israel!