"There are a variety of ways of helping people without putting our troops in - hardware, logistics, expertise, more information-sharing," he said.
The Macedonian Government has given ethnic Albanian rebels until midnight to surrender or withdraw from Macedonian territory.
Otherwise, it says it will use all available means against them.
The Government had said it would only fire on the rebels if its own forces came under attack, but around dawn volleys of gunfire were heard around the town of Tetovo.
On Tuesday afternoon, the Macedonian army and special police launched the heaviest bombardment so far on rebels holding strategic hilltops above Tetovo, the country's second city.
One report form the region says that the Albanian rebels have rejected the ultimatum.
Increasing isolation
The BBC's Bridget Kendall in Macedonia says the rebels are facing increasing diplomatic isolation both at home and abroad, as two Albanian parties inside Macedonia have called on them to lay down their arms.
The United States has reiterated its support for the Macedonian Government. US State Department spokesman Richard Boucher said the US was exploring ways that Nato could give more support to the Government without committing soldiers of its own.
"There are a variety of ways of helping people without putting our troops in - hardware, logistics, expertise, more information-sharing," he said.
The UN Security Council, meanwhile, opened debate on a French-backed resolution condemning the guerrillas.
Russia favours even stronger wording than the French, labelling "armed groups of ethnic Albanians" as engaging in "terrorist activities".
European backing
At a meeting with Macedonian President Boris Trajkovski on Tuesday, European Union foreign policy chief Javier Solana gave his approval to the use of force to push back the guerrillas.
Mr Trajkovski has warned that the future stability of the Balkans depends on the total defeat of ethnic Albanian guerrillas trying to capture territory in the north of his country.
During a stark assessment of the crisis he gave at an international conference in the Macedonian capital, Skopje, Mr Trajkovski said his government would not negotiate with "terrorists", as he called the rebels.
He said ethnic Albanian extremists were threatening his county's sovereignty and territorial integrity.
There is now little hope of a negotiated settlement to the conflict.
The army has moved at least 10 Soviet-made tanks, hundreds of troops and artillery to Tetovo in what the authorities said was preparation for a final push against the rebels.
A statement issued by the rebels called for a peaceful conclusion to the conflict but insisted they were prepared for war.