In an interview with The Associated Press before a visit by NATO leaders next week, Saakashvili said Russia invaded Georgia to keep the ex-Soviet republic out of the Western alliance.
"If NATO sends a sign of weakness - and clearly this invasion was intended to deter, to scare NATO away - if NATO gets scared away, then this will be a never-ending story," Saakashvili said.
Saakashvili has angered Russia by seeking NATO membership for Georgia. The alliance has promised Georgia will eventually join, and a review of its request for a road map to membership is scheduled for December.
He suggested that keeping Georgia out of NATO because of increasing Russian control over South Ossetia and another separatist region, Abkhazia, would be precisely the result the Kremlin intended - and a recipe for forceful intervention elsewhere.
"People are saying, 'Georgia has conflicts, so maybe Georgia cannot be accepted, but maybe we can accept Ukraine.' But if you put it this way, you automatically are going to get conflict in Ukraine."
Saakashvili said NATO nations must stand together and expressed confidence that Russia's use of what Western governments condemned as disproportionate force had strengthened support from some alliance members for Georgian membership.
He said Russia's actions were aimed at "shaking the foundations of the alliance and their decision-making process."
The Kremlin has accused the United States of encouraging Saakashvili to wage war against separatist South Ossetia and of moving to rebuild Georgia's military following the fighting. Saakashvili said he is committed to peaceful solutions to Georgia's territorial disputes and is not seeking robust military aid from the United States.
"We don't expect to get anything from the U.S., we haven't got anything recently from the U.S. and we will not be getting any large-scale hardware or military material assistance from the U.S.," he said. "All this talk about Americans rearming Georgia, or others coming in and rearming Georgia has been just part of the propaganda."
The U.S. Defense Department said Tuesday that it would send an assessment team to Georgia this week to help determine its needs as a way of showing U.S. support for its security.
Saakashvili denied Russian claims that U.S. military aid, which included training Georgian forces, was instrumental in emboldening Georgia to try to retake South Ossetia by force on Aug. 7.
"No matter what kind of theoretical assistance we could have got from anybody, there is no way Georgia can fight wars with Russia," he said.
In Moscow on Thursday, Russian Prime Minister Vladimir Putin, saying Russia had to act when Georgia attacked South Ossetia. Russian forces repelled the offensive and drove deep into Georgia before withdrawing most of the troops and tanks late last month following a cease-fire deal.
Russia has pledged to withdraw its remaining forces still positioned outside Abkhazia and South Ossetia within a month, but says it will keep thousands of troops in the separatist regions themselves for the foreseeable future. It has also recognized them as independent nations, deepening the confrontation with Georgia and the West.
Saakashvili contends that Georgia was acting in self-defense amid increasing Russian support for the separatists and indications of imminent aggression.
"At a certain moment it was clear that the country was facing an existential threat," he said.
He reiterated his promise that Georgia will gain control of South Ossetia and Abkhazia, but said it would rely on legal mechanisms and pressure from the international community to do so.