The statements came as Macedonian officials released further details of Saturday's attack, close to the country's border with Kosovo.
The NLA has been engaged in a violent campaign demanding more rights for ethnic Albanians in Macedonia.
This was the worst single incident of its kind since the conflict began in terms of numbers killed.
It was also the most serious since Macedonian troops and police pushed back the NLA from their positions around Tetovo, 20km to the south-east, in March.
Renewed violence
The Macedonian Ministry of Defence says the soldiers and policemen were on a routine patrol when their convoy was ambushed.
The attack lasted no more than 10 minutes, leaving two armoured vehicles and a jeep destroyed.
Four of the dead were soldiers, four were policemen. Three other men who were injured are now in a stable condition.
Nato Secretary-General George Robertson said he was appalled, and insisted the rebels' would not achieve their aims.
"I condemn the cowardly acts of the extremists and my message is simple: the violence must end and their tactics will not be successful," Mr Robertson said in a statement.
The EU's foreign policy chief, Javier Solana, also condemned the attack.
"I want to appeal to the citizens and the political leadership of the country to pursue and intensify all efforts to promote inter-ethnic understanding," Mr Solana said in a statement.
An NLA guerrilla spokesman, Ali Ahmeti, has denied that his forces were responsible for the attack.
"Most likely, our forces only resisted in self defence," Ahmeti told Reuters news agency.
The authorities say calm has now returned to the area, with the security forces stepping up their patrols.
Talks
Macedonian President Boris Trajkovski has cancelled a visit to Romania and the government is to meet later on Sunday.
Macedonia's main ruling party, VMRO, has been holding talks with its Albanian coalition partner, as well as opposition ethnic Albanian and Macedonian parties, on the creation of a new government.
The BBC correspondent in Skopje, Nick Wood, says it is hoped this could pave the way for many of the political reforms that ethnic Albanians are seeking in the country.
Across the border in Kosovo, the Nato-led peacekeeping force, K-For, says it has stepped up surveillance along the frontier both on the ground and in the air.
But our correspondent says such reassurances have been given by the alliance before, but seem to have had little impact on the rebels' activities.