WASHINGTON - The United States is focusing on maintaining "a good, positive, healthy military-to-military relationship with the Pakistani army", a top Pentagon official based in Afghanistan has said, while noting that there was no "blow back" from Pakistan after a US drone strike killed Taliban chief Mullah Mansour last month.

At the same time, Army Brigadier General Charles Cleveland, deputy chief of staff for communications, Resolute Support Mission, Afghanistan, did admit "some tension" in the ties.

Asked if there has been a "visible blow back" from Pakistan after Mansour's killing, Gen Cleveland said: "In this case, we haven't yet. And we certainly hope not," Cleveland told Pentagon reporters in Washington during a video conference from Kabul.

"That is part of the effort that General (John) Nicholson (Commander of US and NATO forces in Afghanistan) takes in terms of engaging his counterparts. But at this point, we have not really seen any military-to-military issues," he said.

Cleveland was responding to questions on the sharp reaction from Pakistan after a US drone strike killed Mansour in Balochistan on May 21, with Pakistani officials saying that the air strike "violated its sovereignty". Pakistan Army Chief Gen Raheel Sharif also weighed in, describing the US drone strikes in Pakistani territory as "regrettable".

"Clearly, there is still some tension and there is some back-and-forth. What we're trying to focus, though, is sustaining and maintaining the military-to-military relationship that we've already got established. And that really starts with General Nicholson and goes down a couple of different levels," Cleveland said.

"So by and large, what we're trying to focus on is ensuring that we maintain a good, positive, healthy military-to-military relationship with the Pakistani military," he added.

GUNMEN KIDNAP 17 IN NORTHERN AFGHANISTAN

AFP adds: Gunmen on Thursday kidnapped at least 17 people travelling in civilian vehicles in northern Afghanistan, officials said, in the second group abduction within a week, underscoring the worsening security situation in the country.

The passengers, all minority Hazaras, were pulled out of their vehicles in Sancharak district in Sar-e-Pul province and taken to a remote area controlled by Taliban insurgents, the local governor said.

"They are all innocent civilians with no government connections. We have asked local elders to talk to the Taliban commanders and secure their release," Governor Zaher Wahdat told AFP.

There was no immediate comment from the Taliban.

The three-million-strong Afghan Hazara community has been persecuted for decades, with thousands killed in the late 1990s by Al-Qaeda and the Taliban.

There has been a surge in violence against the community, with a series of kidnappings and killings in recent months that have triggered a wave of fury on social media.

The incident occurred two days after the Taliban killed 10 bus passengers, many of them summarily executed, and kidnapped dozens of others in northern Kunduz province.

The insurgents said they were targeting Afghan security officials aboard the buses passing through the insurgency-prone district of Aliabad, as the insurgents step up their annual spring offensive after naming a new leader last week.

Hundreds of people chanting "Death to Taliban" protested in Kabul on Thursday against the violence in Kunduz.

"How long will people have to suffer bloodshed?" said protester Sayed Mohammad. "Neither government staff nor civilians are safe to come out of their homes."

The UN Assistance Mission in Afghanistan voiced concern over the growing incidents of attacks against civilian vehicles.

"Taking civilians hostage is indefensible," UNAMA chief Nicholas Haysom said in a statement.

"I call for the immediate and unconditional release of all civilians detained and a halt to this horrible practice."

The Taliban last week announced Haibatullah Akhundzada as their new leader, elevating a low-profile religious figure in a swift power transition after officially confirming the death of Mullah Mansour in a US drone strike.

The drone attack was the first known American assault on a top Afghan Taliban leader on Pakistani soil.

Observers say Akhundzada, who is seen as more of a spiritual figurehead than a military commander, will emulate Mansour in shunning peace talks and intensifying attacks against the Afghan government.