The officials say Shiite rebels known as Houthis were trying to retake the western part of the city yesterday, while a Saudi-led coalition launched more than a dozen airstrikes to prevent the Houthis from advancing.
Yemen's civil war pits Houthi rebels against fighters allied with the internationally recognised government.
A Saudi-led coalition began launching airstrikes against the Houthis in March 2015. The Houthis had besieged Taiz for over a year until pro-government forces pushed them out of the western part of the city last week, reopening a passage into Taiz.
All officials spoke on condition of anonymity because they were not authorised to brief reporters.