"Are you with us or with Qatar?" the king asked Sharif, according to a diplomatic source cited by The Express Tribune, a Pakistani affiliate of The New York Times on Wednesday.
Having remained publically neutral on the matter, it seems that Sharif has snubbed Salman's ultimatum and kept his country neutral in the diplomatic rift.
Pakistan, which is the only Muslim country to possess nuclear weapons, would prove an influential ally for Saudi Arabia in its ongoing rift with Qatar.
If the report is reliable, Pakistan's decision marks a brave move for the South Asian country, which like Saudi Arabia has been linked to the funding and harbouring of extremist Islamist groups.
Pakistan is already locked in disputes with neighbouring Afghanistan and India, both of whom accuse Islamabad of funding Sunni insurgencies abroad.
Moreover, Pakistan is still mending ties with the United States, after years of suspended military cooperation following the revelation that deceased al-Qaeda leader Osama bin Laden was hiding in the country's northeast.
The breaking off of diplomatic ties with Qatar by Saudi Arabia, Egypt, Bahrain and the United Arab Emirates came after Trump's visit to the Middle East in May.
The Saudi-led bloc accuses Doha of funding terrorism and destabilising the region - charges which Qatar has vehemently denied.