This information was also not included in the report last quarter from the Special Inspector General for Afghanistan Reconstruction - which was set up by Congress to audit US spending in the country's longest-running war.
The Pentagon has denied being responsible for the request to block the publishing of the information.
He said suicide bombings are against Islam and against humanity.
"It was NOT the intent of Resolute Support to withhold or classify information which was available in prior reports", Gresback said in an email. "A human error in labeling occurred", US Navy Capt. Tom Gresback, a spokesman for the operation, told CNN.
"The classification system, because it incorporates both a North Atlantic Treaty Organisation and U.S. nomenclature, can be challenging, and a mistake was made".
The auditing agency, established by Congress and known as the Special Inspector General for Afghanistan Reconstruction, or SIGAR, revealed the new gag order in a three-month assessment of conditions in Afghanistan released overnight.
The United States aims to press the Taliban on the battlefield to convince them that they will have to negotiate peace, a senior USA diplomat said on Tuesday, a day after President Donald Trump rejected talks following a series of attacks.
Trump rejects bipartisan immigration proposal
The White House spokeswoman also addressed an ad that Trump's re-election campaign put out over the weekend to hammer out a deal. Republican Senator Susan Collins said the discussions could lead to several proposals, not just one piece of legislation.
The expanded authorities provided [by President Trump] to USA forces in Afghanistan have resulted in a significant uptick in US air strikes and special operations against the insurgency, with the USA dropping 653 munitions in October 2017, a record high since 2012 and a more than three-fold increase from October 2016.
In a statement released on Tuesday, the ministry said: "We learned with sorrow that a terrorist attack targeting the Military Academy in Kabul, resulted in the loss of lives of many Afghan soldiers and left many others wounded". More than 90 people were dead and another 158 received fatal injuries in the suicide attack. The goal of the Afghan government is to control 80% of its population within the next two years.
Hamidullah Mohib, the Afghan envoy to the United States, did not respond to questions about Qarar's tweets, PTI reported on Tuesday.
Additional reporting from Newsy affiliate CNN.
The Afghan government's control over the population is a higher percentage number than its control over districts, as rural and less populated districts tend to be where the Taliban are strongest.
While U.S. policy has always been to use military pressure to force the Taliban to the negotiating table with the Afghan government, Trump said on Monday that "innocent people are being killed left and right" so "we don't want to talk with the Taliban".