The explosion before dawn at Garai bazaar in Miran Shah, the main town in the North Waziristan tribal region, smashed windows, doors and goods at about 10 shops.
Many of the shops sold TV sets, audio and video cassettes and rented out music and movie CDs, an intelligence official in Miran Shah said.
No one claimed responsibility.
Aljazeera reported that an organisation calling itself the al-Qaida Group threatened in a statement to attack video shops and hotels that promote what it called immoral values in the country.
The unnamed official said pamphlets had been distributed in Miran Shah five days earlier warning that unless all video rental shops and stores selling television sets, audio and video cassette players closed, they risked being attacked.
The pamphlets, in Pakistan's main Urdu language, also warned hotel owners against having TVs in rooms or showing movies to their guests, the official said.
Radical Muslim groups - like Afghanistan's Taliban, vanquished from power in late 2001 - consider films and the playing of music as against Islam. The Taliban banned televisions and nearly all other forms of entertainment.
Aljazeera reported that the Muslim Scholars Society, headed by Mawalana Fazur Rahman, held a rally in Miran Shah.
Thousands of tribesmen at the rally demanded an end to Pakistani military operations in the region.
They also denounced calls of moderation by Pakistan's president, General Pervez Musharraf, as spreading immoral values under slogans of reform.
Pakistan, a key ally of the United States in the "war against terrorism", has deployed thousands of troops to the north and the adjoining South Waziristan regions, which both border Afghanistan, to track down fighters.
The authorities think hundreds of Arab, Central Asian and Afghan fighters, suspected of links with al-Qaida, are hiding in the region.