Turkey's President Recep Tayyip Erdogan faced noisy protests on Thursday as he confronted critics in Washington, defending his media crackdown and accusing the West of turning a blind eye to Kurdish violence.

The White House said that US President Barack Obama had met Erdogan on the sidelines of a nuclear security summit in the US capital, but the absence of a formal presidential meeting between the pair appeared to highlight the simmering diplomatic tensions between the NATO allies with sharply differing views over the war in Syria.

A White House spokesperson said Obama and Erdogan had discussed "US-Turkey cooperation on regional security, counterterrorism, and migration," while Erdogan also held formal talks with US Vice President Joe Biden.

Erdogan's arrival in Washington coincided with another deadly bomb attack targeting police in Turkey's Kurdish-majority southeast, where his forces are battling Kurdish militants which Ankara says are allied to the YPG, the main Kurdish fighting force in Kurdish areas of northern Syria.

The Turkish government regards the YPG as an affiliate of the PKK, Turkey's main Kurdish separatist movement, and has declared it a “terrorist threat” whereas Washington sees the YPG as a key ally in its campaign against the Islamic State (IS) group.

Erdogan was confronted with protests as he arrived to deliver a speech at the Brookings Institute security think tank, with Turkish security officials clashing with the crowd - both sides exchanging insults and scuffling - before local police were able to separate them.

The Turkish guards also came into conflict with news media. One aimed a chest-high kick at an American reporter attempting to film the harassment of a Turkish opposition reporter; another called a female foreign policy scholar a "PKK whore".

Turkish security tried to bar two Turkish journalists, one of them working for the Zaman newspaper that has been seized by the government, from entering.

Brookings staff prevented Turkish officials from driving out the journalists, who had been invited to cover the event, amid tense scenes.

Meanwhile, outside, pro-Kurdish demonstrators chanted: "Erdogan, fascist" and "Erdogan, baby-killer".

Kurdish protesters chanted anti-Erdogan slogans (AFP)

But Erdogan appeared unruffled as he delivered a forceful address in which he ceded no ground to critics at home or abroad.

On the renewed battle with the Kurds, Erdogan claimed that the PKK and the YPG were one and the same, and said that there was no difference between the two Kurdish groups and IS.

"Terrorists unfortunately keep attacking our country," he said. "We cannot tolerate this anymore. European countries and other countries, I hope they can see the true face of terrorists in these attacks."

Erdogan complained that just because the YPG were fighting against IS with Western support, some saw them as what he derisively termed "good terrorists" and complained that they had backers in Europe.

"I know people are organising, funding meetings, and are assisting in getting arms to those organisations," he said.

The US-led coalition has made no secret of its ties with Kurdish militias in northern Syria and US officials do not regard the YPG as an auxiliary of the PKK, which Washington does deem a terrorist group.

Erdogan was also firm in his defence of Turkey's recent crackdown on the press.

"There's no difference between a terrorist with a gun and bomb in his hand and those who exploit their positions, pens and titles and put them at terrorists' disposal to achieve their aims," Erdogan said earlier in March.

"The fact that they are MPs, academics, writers, journalists, NGO executives does not change the fact that they are terrorists.

"Those who explode the bomb and pull the trigger can be terrorists but those who help that action achieve its goal are their supporters and abetters."

In mid-March, Turkey's president urged the country’s parliament to strip pro-Kurdish MPs of immunity from prosecution, days after he said he was seeking to widen the definition of terrorism and as Turkish police arrested eight lawyers in a crackdown on pro-Kurdish activists.