Libyan Prime Minister Ali Zeidan has said the government is safe and security under control, describing rumours of a coup "ridiculous".
Zeidan's remarks on Friday came in response to a senior army official's call for parliament to be suspended and for the armed forces to "rescue" the country.
Major General Khalifa Haftar, a leading figure in the 2011 revolution against Muammar Gaddafi, called for a presidential committee to be formed to govern until new elections could be held in what he described as a road map for Libya.
"No military units have moved to touch any institutions."
Nearly three years after Gaddafi's fall, Libya has had only fragile government and armed forces unable to impose their authority on competing political factions and the brigades of former revolutionary fighters who refuse to disarm. Libya still has no new constitution.
"Libya is stable. The [General National Congress] GNC is doing its work and so is the government. The army is in its headquarters, and Khalifa Haftar has no authority," Zeidan told Reuters. "No military units have moved to touch any institutions."
He said legal proceedings under military law would be taken against Haftar for his statement.
Tripoli was calm, and there were no signs of any extraordinary troop movements or activity outside the parliament, the prime minister's office or any ministries.
It was not clear how much influence Haftar has even within the small, nascent army in a country where brigades of militia groups and former rebels are more powerful.
Appearing in military uniform, Haftar, in his recorded statement provided to Reuters, called for the GNC, the interim parliament, to be suspended.
"The national command of the Libyan army is declaring a movement for the new road map," Haftar said, adding that the armed forces were calling for Libya to be "rescued" from its upheaval.
"We will hold meetings with different parties and groups regarding implementing this road map," he said.
Libya's army barely exists with most of its soldiers still in training or drawn from the ranks of former rebels who are often more loyal to their own regions, their commanders or their tribes than a national force.
Haftar was once a Gaddafi ally, but broke with him over the war with Chad in the 1980s. He later sought exile in the United States, but returned to become a commander of forces in the 2011 revolution.
The General National Congress is deeply split by infighting between the nationalist National Forces Alliance party and Islamists in the Justice and Construction Party, which is tied to the Muslim Brotherhood, and the Al Wafaa movement.
Since its election in 2012, the GNC has become increasingly unpopular with Libyans who see it has made little progress in the transition to democracy. Libya still has no new constitution.
But tensions have increased over its future, after its initial mandate ran out on February 7. Its members agreed to extend their term in office to allow a special committee the stability to draft the constitution.
Rival political factions and militia groups have competing views on how the country should continue, with some calling for early elections and others supporting the extension of the parliament's mandate.