Jaap de Hoop Scheffer said Russian force was "disproportionate"
Nato's secretary general has said he hopes for Georgia's "accelerated" integration with Nato, and condemned Russia's conduct in August's conflict.
However Jaap de Hoop Scheffer, speaking in Tbilisi at the first meeting of the Nato-Georgia Commission, did not say when Georgia might join the alliance.
And he emphasised that the country still had to make democratic progress.
Georgian President Mikhail Saakashvili welcomed the visit as a "powerful signal" of solidarity.
"Your presence sends a... signal to the world that Georgia, together with its friends and allies, does not stand alone," Mr Saakashvili told Mr de Hoop Scheffer and the ambassadors of the 26 Nato countries gathered in Tbilisi.
"Russia's use of force was disproportionate and Russia must now comply with all elements of the six-point plan," Mr de Hoop Scheffer said, referring to the EU-brokered ceasefire deal that calls for all forces to withdraw to positions occupied before the conflict.
"At the same time, despite the difficult situation, we expect Georgia to firmly stay the course of democracy and reform," the Nato chief added.
Earlier he said the post-conflict situation was "difficult to swallow", since Russia appeared intent on maintaining troops in Georgia's breakaway regions of South Ossetia and Abkhazia.
"If the Russians are staying in South Ossetia with so many forces, I do not consider this as a return to the status quo," he told the Financial Times.
Mr de Hoop Scheffer did not say whether Georgia would be given a Membership Action Plan - a roadmap for accession - when Nato meets for a summit in December.
The EU has offered money to help displaced people
Nato countries are divided, says the BBC's diplomatic correspondent Jonathan Marcus.
While they are keen to offer Georgia fulsome support, he says, Nato rules say that ethnic disputes or external territorial disputes must be resolved before membership can be offered.
The conflict in the region began on 7 August when Georgia tried to retake South Ossetia by force after a series of lower-level clashes.
Russia launched a counter-attack and the Georgian troops were ejected from both South Ossetia and Abkhazia.
Also on Monday, the EU announced 500m euros (£397m, $712m) in aid to help Georgia's recovery.
European Commissioner Benita Ferrero-Waldner said the funds would go to assisting internally displaced people, post-conflict rehabilitation and economic recovery, and towards new infrastructure.
In Brussels, European Union foreign ministers were set to clear the way for at least 200 ceasefire monitors to deploy to buffer zones around South Ossetia and Abkhazia, ahead of an expected Russian troop withdrawal by 10 October.
It is unclear whether the monitors will actually be allowed to enter the breakaway regions, which are full of Russian troops.
Russia has recognised the two regions' independence, and President Dmitry Medvedev said he would sign agreements this week formalising diplomatic relations and establishing military links.
Moscow has already announced that it intends to base 3,800 troops in each of the two regions.