Afghanistan's government has lashed out at Imran Khan after the former Pakistan cricket star, now a politician, said the Taliban were fighting a "holy war" in the country that was justified by Islamic law.

Speaking after visiting a hospital in Peshawar where Malala Yousafzai – the 14-year-old activist shot in the head by the Taliban for supporting girls' education – was treated last week, Khan told reporters that insurgents in Afghanistan were fighting a "jihad". Citing a verse from the Qur'an, he said: "It is very clear that whoever is fighting for their freedom is fighting a jihad …

"The people who are fighting in Afghanistan against the foreign occupation are fighting a jihad," he added, according to a video of remarks to journalists.

Afghan politicians have reacted with disbelief, with one parliamentarian suggesting Khan should be arrested. The Ulema Council, a grouping of senior clerics, declared his comments "unislamic".

A Kabul foreign ministry spokesman said Khan was "either profoundly and dangerously ignorant about the reality in Afghanistan, or he has ill will against the Afghan people.

"Our children are killed on daily basis, civilians killed and our schools, hospitals and infrastructure attacked on a daily basis. To call any of that jihad is profoundly wrong and misguided."

Hamid Karzai, the Afghan president, has written to all of Pakistan's political leaders, including Khan, saying: "We must ask why we have been unable to counter the terrorism that is attacking our people, and the promise of a better future for our children."

Khan has also courted criticism by saying he will not publicly name the Taliban while criticising the men who attempted to kill Malala, because he feared it would put his party's supporters at risk.

The row with Kabul highlights the awkward political situation Khan has found himself in recent days. He has long blamed the rise of the Taliban in the country on the US, saying its military operations in Afghanistan and the CIA drone strikes in Pakistan's tribal belt are responsible for the upsurge in militancy.

But his populist position has been challenged by the almost unprecedented public anger against the Pakistani Taliban triggered by the attempt to kill Malala as she sat in a van with her classmates in Swat last Tuesday.

While many observers fear the mood of national outrage will ultimately change little, the country's media continues to cover the saga intensively while the country's powerful military chief called on the nation to "unite and stand up to fight" against extremism.

The foreign minister has even suggested the attack might be a turning point for a country that has long struggled to muster support for a decisive push against militants. On Sunday, tens of thousands of people attended a rally in Karachi in support of Malala, organised by the Muttahida Qaumi movement, the dominant political party in the southern city.

Malala is unconscious and in intensive care in a military hospital in the garrison city of Rawalpindi. A military spokesman said her condition was improving and that no decision had been made as to whether she should be sent overseas, despite an offer from the United Arab Emirates to supply an air ambulance.

Local media continued to focus on her condition despite government warnings that the Pakistani Taliban, apparently angered by criticism of the attack on Malala, had ordered attacks on journalists.