Nine players and three officials tested negative for the new coronavirus after they were found to have spent time outside the bubble area near their hotel.
The people, identified only as senior players and officials, received warnings and were made to pay for the tests, the board said in a statement.
"They have put at risk the integrity of the tournament and, health and safety of their colleagues," PCB director of high performance Nadeem Khan said in the statement, adding that the board was "disturbed and disappointed."
"This is completely unacceptable to the PCB and following meetings with the concerned players and their team officials, it has been agreed there will be zero-tolerance for future breaches, and those violating the protocols will be expelled from the ongoing and future tournaments."
Pakistan is scheduled to host Zimbabwe for three one-day internationals and as many Twenty20 matches in Rawalpindi and Lahore in a limited-overs series starting on Oct. 30.
"I expect the players and officials to show responsibility as the world is watching and international cricket is standing at our doorsteps," Nadeem said.
"Their irresponsible actions can put into jeopardy all the efforts of the PCB in organising and inviting sides during these challenging COVID-19 times." (Reporting by Sudipto Ganguly in Mumbai; Editing by William Mallard)