Sharif, wife Kulsoom and daughter Maryam were heading back from Mureee hill resort to Islamabad yesterday when a private vehicle came dangerously close to their car near Malpur area.
According to police, officials on the security detail of the prime minister quickly reacted and stopped the vehicle intruding the convoy, and arrested its driver.
The driver, a former officer of the Pakistan Air Force, intentionally came close to Sharif's vehicle while driving through a narrow stretch, police spokesman Muhammad Naeem said.
The spokesman did not disclose the identity of the driver.
Sharif often travels incognito with minimum security to Murree, one of his favourite resorts. The road usually remains open for public transport during his movements.
Sharif's security, however, has been beefed up after the death of the chief of banned Lashkar-e-Jhangvi, Malik Ishaq, last month in a shootout with police.