Brigadier Prasad Samarasinghe, the army spokesman, also said the crossing points to Tamil Tiger territory was reopened on Thursday
While the heavy firing of Tuesday night and Wednesday has ceased, both sides have said they will retaliate if attacked again.
If violence halts, diplomats say peace talks might still be possible. If not, many fear that the 2002 ceasefire can collapse completely.
A suicide bomb attack that killed 10 and wounded the army's commander on Tuesday was followed by air strikes on Liberation Tigers of Tamil Eelam (LTTE) territory in the east. The United Nations says thousands have fled from their homes.
The pro-rebel website Tamilnet quoted S Elilan, LTTE's north-eastern political chief, as saying that the rebels awaited instructions from their leadership. He added that any retaliation would be "catastrophically disabling and devastating to our enemy".
The army spokesman said there had been no new military action overnight, but that an army camp near rebel territory in the northeast had been fired on with small arms. He would not say if that would prompt retaliation.
The Tigers say more than 12 civilians were killed in the government air and artillery strikes on their territory around the north-eastern port of Trincomalee. They also say about 40,000 people have fled from their homes.
Aid workers say that figure is probably an overestimate, but the United Nations High Commissioner for Refugees (UNHCR) said it believed thousands had been displaced.
Dangerous times ahead
The International Committee of the Red Cross said it hoped to get security guarantees from both sides so it could move in.
Tamil say the bombing and ongoing
killings are attempted genocide
In the northern army-held but Tamil-dominated Jaffna enclave, a Reuters reporter said residents were hoarding food and that a shortage of fuel was affecting public transport and electricity supplies, with no new supplies coming up through Tiger territory.
The army said the border reopened early on Thursday and government officials said fuel was being sent.
Diplomats said the international community - including neighbour India - had wanted the bombing halted to allow aid shipments.
Military experts also said the air force lacked the capability for precision strikes and civilians were likely to have been hit.
"Even if they have stopped, the door is still open for many dangerous moments ahead," said a Western diplomat.
Some feel the Tigers, whose two-decade fight for a Tamil homeland in the north and east has killed more than 64,000 people on both sides, feel they have not achieved enough from peace and are looking for a reason to restart the conflict.
"The terror atmosphere that has been created throughout the Tamil homeland has shattered the Tamil people"
LTTE's official website
Others say they have more limited goals and are angry that the government has done nothing to rein in renegade ex-rebels, the Karuna group, who Nordic truce monitors say have been operating from government territory and attacking the mainstream rebels.
The reason the rebels gave for pulling out of peace talks in Geneva is more mundane still - a dispute over the transport of eastern rebel leaders to a pre-talks meeting. Mediator Norway and the truce monitors are still trying to overcome that hurdle.
In an official statement, the Tigers said the bombing and ongoing killings of Tamil civilians amounted to "attempted genocide", and called for the international community to condemn and immediately stop the attacks.
"The terror atmosphere that has been created throughout the Tamil homeland has shattered the Tamil people," said a statement on their official website. "Today, Tamil people are seeking and expecting protection from our movement."