Top rebel military commander Koteshwar Rao, also known as Kishenji, made the offer through a statement to TV and newspaper offices late on Monday, saying the ceasefire could hold from Feb. 25 to May 7.
But the government said "in the absence of an authentic statement" it was unable to respond immediately, raising doubts the Maoist truce offer would pave the way for peace talks to end decades of insurgency.
Home Minister Palaniappan Chidambaram said in a statement that talks could be possible if the rebels gave up violence, a demand the Maoists have so far refused.
"I would like no ifs, no buts and no conditions," Chidambaram said. "Once I receive the (truce offer) statement, I shall consult the prime minister ... and respond promptly."
The Maoists, described by Prime Minister Manmohan Singh as the country's biggest internal security threat, regularly ambush police, and attack railway lines and factories aiming to cripple economic activity.
The rebels carried out more than 1,000 attacks last year in the countryside and some bigger rural towns, killing more than 600 people and disrupting movement of coal and bauxite in mineral-rich eastern and central India.
The Maoist truce offer comes a week after the rebels killed 35 people in back-to-back attacks in two states, including a daylight attack on a police camp that raised a storm of criticism over India's ability to tackle the threat.
The rebels, whose numbers are believed to be between 22,000 and 25,000, have also been under pressure from a massive, coordinated government security offensive and many believe the truce offer is a ruse to regroup.
Some analysts also point out that the truce offer covers the months when trees shed their leaves making it difficult for the rebels to move around their jungle hideouts.
"We are for the first time carrying out a coordinated movement against them. Yes, they might have had some success through their hit-and-run tactics, but the heat is on them," a senior internal security official told Reuters on Monday.
The Maoists say they are fighting for the rights of poor peasants and landless labourers, and blame the federal government for doing little for the welfare of poor tribals.
The rebels feed off the resentment of millions of poor people who have not shared the benefits of the boom in India's economy, which, after the global slowdown, looks set to climb back to more than 8 percent growth in the next fiscal year.
They control a narrow corridor of forested, mineral-rich belt stretching over 22 of 28 states. But their influence remains largely restricted to the countryside and small towns.