Donald Trump and Barack Obama. Win McNamee/Getty Images President-elect Donald Trump on Wednesday lit into President Barack Obama's comments about how he could have defeated Trump to win a third term and again criticized his administration's decision to abstain from a critical United Nations Security Council vote on Israel.

"Doing my best to disregard the many inflammatory President O statements and roadblocks," Trump tweeted Wednesday. "Thought it was going to be a smooth transition — NOT!"

Obama said in an interview with former senior adviser David Axelrod published Monday that he thought he would have won if he had run this year. Trump quickly tweeted a response: "NO WAY!"

Trump's about-face on Obama comes after the two had enjoyed a mostly chummy relationship during the presidential transition.

Trump also criticized the US's decision to abstain from the vote on a UN Security Council resolution urging Israel to stop building settlements on occupied Palestinian land.

The move further strained the relationship between Israeli Prime Minister Benjamin Netanyahu and Obama. Tensions had already been heightened because of the US-led nuclear negotiations with Iran and Obama's longstanding opposition to Israel's settlement policy.

"We cannot continue to let Israel be treated with such total disdain and disrespect," Trump tweeted. "They used to have a great friend in the US, but ... not anymore. The beginning of the end was the horrible Iran deal, and now this (UN)! Stay strong Israel, January 20th is fast approaching!"

Israel's ambassador to the US said earlier this week that Israel would show Trump evidence that the Obama administration was behind the Security Council resolution. A senior Israeli Cabinet minister also on Wednesday said a planned speech by US Secretary of State John Kerry on Middle East peace was "pathetic."

Later Wednesday, Trump said he and Obama spoke on the phone and had a "very nice conversation." He again criticized the UN.

"The UN has such tremendous potential, it's not living up to its potential," he said.