A formal announcement to this effect will be made in a few hours, the officials said.
"We have been asking them repeatedly to put in place an effective mechanism for blocking immoral and indecent content," one of the top officials directly involved in the decision told Reuters.
"The platform, however, hasn't been able to fully satisfy Pakistani authorities. The decision has been taken to block TikTok for accessing in Pakistan," he said.
In July, Pakistan's telecommunications regulator issued a "final warning" to the short-form video app over explicit content posted on the platform.
TikTok, owned by China-based ByteDance, has been caught in a firestorm globally due to security and privacy concerns. It has already been blocked in India and it faces scrutiny in countries from Australia to the United States.
TikTok was not immediately reachable for comment on the matter.
The decision was taken after Pakistani Prime Minister Imran Khan took a keen interest in the issue, said a second official in Pakistan, adding that Khan has directed the telecom authorities to make all efforts to block vulgar content in the conservative Islamic republic.