The world governing body said local officials could instead be appointed by the Pakistan Cricket Board.
There will be two Twenty20 and three one-day internationals from 22-31 May.
On Thursday Zimbabwe cancelled the tour after news of a terrorist attack in Karachi, then retracted the statement.
No top-level international cricket has been played in Pakistan since Sri Lanka's team bus was attacked there by gunmen in 2009.
The International Cricket Council will not send umpires to Pakistan to officiate in their upcoming limited-overs series against Zimbabwe because of security concerns.