The website of police in the garrison city, which neighbours the capital Islamabad, was plastered with photographs and videos of Al-Qaeda and Pakistani Taliban leaders and a message saying "Hacked By Anti Mortadin!@".
It was unclear who the hackers were with no group claiming responsibility for the cyber-attack.
"This site was hacked... A victory for the Taliban," said another post. A Taliban spokesman was not immediately available for comment.
A police official in Rawalpindi confirmed the hacking, telling AFP that no sensitive data had been breached as the website was mostly used for public awareness campaigns.
"The website had no sensitive information. We have started repairing it and blocked further access," the official added.
Since the Tehreek-e-Taliban Pakistan (TTP) rose up against the Pakistani state in 2007, more than 6,800 people have been killed in bomb and gun attacks across the country, according to an AFP tally.