Democratic presidential candidate Hillary Clinton, U.S. President Barrack Obama, and Philippine President Rodrigo Duterte.

Democratic presidential candidate Hillary Clinton on Wednesday said U.S. President Barack Obama made the right decision to cancel his meeting with Philippine President Rodrigo Duterte.

"With respect to the Philippines, President Obama made exactly the right choice," Clinton told reporters on her campaign plane. "When you meet with anyone, ally or adversary, you come in with a list of issues that are important to be raised. You determine what they are."

Expletive-laden comments made by Duterte regarding the U.S. and Obama before he left for the Association of Southeast Asian Nations (ASEAN) summit on Monday have resulted in Washington calling off a bilateral meeting between the two nations.

Duterte threatened to curse at Obama if the American leader voices concern over the Philippines' brutal campaign against drugs and crime. Duterte later sought to defuse the row, voicing regret.

The two had been scheduled to meet on the sidelines of the ASEAN summit in Laos.

READ: Duterte hits US anew before leaving for ASEAN Summit

READ: Duterte 'regrets' comments vs. Obama, hopes to resolve spat

Clinton said Obama wanted to raise the issue of extra-judicial killings in the Philippines under the Duterte administration's ongoing war on illegal drugs.

"On the other side, they determine what they want to raise. And clearly the president was going to raise concerns that are global about what is going on in the Philippines with extrajudicial killings of alleged drug dealers, that is now somewhere up near 2,000 killings," she said.

"When the president of the Philippines insulted our president, it was appropriate and a very low key way to say: sorry, no meeting. And since then there's been an apology and an expression of regret, which is appropriate," Clinton added.

'Words matter'

Obama's planned meeting with his Philippine counterpart was canceled because the tone of Duterte's rhetoric raised questions about the chances for a productive talks, the U.S. State Department also said on Tuesday.

"Words matter, and we want to see an atmosphere that is cordial and open to strong cooperation," State Department spokesman Mark Toner said.

Clinton's Republican rival, Donald Trump, on the other hand took to Twitter to take potshots at Obama over Duterte's expletive and China's treatment of the current U.S. president.

"China wouldn't provide a red carpet stairway from Air Force One and then Philippines President calls Obama 'the son of a whore.' Terrible!' Trump said.

China wouldn't provide a red carpet stairway from Air Force One and then Philippines President calls Obama "the son of a whore." Terrible! — Donald J. Trump (@realDonaldTrump) September 6, 2016

Duterte's regret

Duterte has issued a statement saying he hopes to resolve his spat with Washington, a long-time ally of the Philippines.

"While the immediate cause was my strong comments to certain press questions that elicited concern and distress, we also regret that it came across as a personal on the US President," he said in a statement read by Presidential spokesperson Ernest Abella.

"Our primary intention is to chart an independent foreign policy while promoting closer ties with all nations, especially the US with which we have a had long standing partnership," he said. "We look forward to ironing out differences arising out of national priorities and perceptions, and working in mutually responsible ways for both countries."

Duterte clarified that he gave his consent to the cancellation of what would have been his first meeting with the US leader.

"The meeting between the United States and the Philippines has been mutually agreed upon to be moved to a later date," he said.

But Presidential peace adviser Jesus Dureza admitted that the meeting has yet to be rescheduled.

"It's being moved to a later date, so let's wait when that date will be announced," he said.

The perceived strain on the US-Philippine relations comes as Manila seeks to reinforce a tribunal ruling that invalidated the historic claims of China to the resource-rich South China Sea. - with reports from Reuters