They note that if production were as understated as the committee alleged, Bulyanhulu and Buzwagi, the two mines where it produces concentrate, would be the biggest gold producers in the world.
The firm says that it “wishes this were true, but sadly it is not the case.”
Its gold production is audited in its accounts.
How far Mr Magufuli wishes to go is unclear.
The big fear is that he may favour full nationalisation.
But he may accept a more pragmatic settlement.
Analysts at UBS, a bank, reckon the Tanzanian government wants to bully Acacia into giving up a share of its “tax assets”, which it values at $532m.
For example, the company is owed some $150m in VAT refunds.
Barrick, which owns almost 64% of Acacia, will discuss all of this.
“A negotiated solution is better than escalation, such as going to international arbitration,” a spokesman says.
That means it is prepared to talk about the tax problem as well as the possible construction of Tanzania's first smelter of gold- and copper-concentrates, even though the latter has long been considered uneconomic because the country's output of concentrates is too low.
Since the ban was imposed, Acacia has continued to mine, stockpiling its output instead of exporting it.
But it cannot continue without generating cash for ever.
If it stops production, the damage will extend to the country at large.
Last year Tanzania's economy was among Africa's best performers, growing by about 6%.
It needs more foreign investment to maintain that pace.
Mr Magufuli's tactics—whether he has God and the angels on his side or not—will make that harder to achieve.