Apple has accused the US Justice Department of trying to "smear" the company with "desperate" and "unsubstantiated" claims.
It followed the Justice Department's latest court filing over its demand that Apple create software to unlock an iPhone used by an attacker in a mass shooting last year, BBC reported.
The department said that Apple's stance was "corrosive" of institutions trying to protect "liberty and rights".
It also claims Apple helped the Chinese government with iPhone security.
Apple's general counsel Bruce Sewell said: "The tone of the brief reads like an indictment."
He said: "Everybody should beware because it seems like disagreeing with the Department of Justice means you must be evil and anti-American, nothing could be further from the truth."
Prosecutors claim Apple's own data shows that China demanded information from Apple regarding more than 4,000 iPhones in the first half of 2015, and Apple produced data 74 percent of the time.
But Sewell said the new filing relies on thinly sourced reports to inaccurately suggest that Apple had colluded with the Chinese government to undermine iPhone buyers' security.
The US government has been fighting Apple over access to information on the iPhone used by one of the San Bernardino killers, Rizwan Farook, in December. Apple says the demands violate the company's rights.
The Department of Justice claimed in its court filing that Apple had attacked the FBI investigation as "shoddy", and tried to portray itself as a "guardian of Americans' privacy".
This "rhetoric is not only false, but also corrosive of the very institutions that are best able to safeguard our liberty and our rights: The courts, the Fourth Amendment, longstanding precedent and venerable laws, and the democratically elected branches of government," the DoJ said.
In February, the FBI obtained a court order to force Apple to write new software that would allow the government to break into the phone. The FBI wants the software to bypass auto-erase functions on the phone.
Apple has argued that the government is asking for a "back door" that could be exploited by the government and criminals.
The tech giant has filed its own court request that the ruling be overturned, arguing that the order violated the company's constitutional rights.
"This case is about the Department of Justice and the FBI seeking through the courts a dangerous power that Congress and the American people have withheld," Apple said.
The iPhone maker has received support for other tech giants including Google, Microsoft and Facebook.
The FBI said Farook and his wife, Tashfeen Malik, were inspired by Islamic State militants when they killed 14 people at a party on December 2.
The couple later died in a shootout with police and the FBI said it wants to read the data on Farook's work phone to investigate any links with militant groups.
A hearing into the case is scheduled for March 22 in a California federal court. Apple chief executive Tim Cook has said he was willing to take the case to the Supreme Court.
