Which parties in particular are we talking about internationally? The traditional great powers of Europe? The Franco-Prussian War was an epoch-defining event that shook up the traditional order in central Europe, which allowed the Prussians and the North German Confederation to formally unite the southern German kingdoms of Württemberg, Baden, and Bavaria into a single, German state. Any balance-of-power equations that would have existed prior to 1871 about a fractious, disunified Germany, would have to have been re-evaluated.
An important aspect of why there was little fervor to really intervene on the side of France during the war was because of diplomatic maneuvering on the part of Prussian Chancellor Otto von Bismarck to diplomatically isolate France by the time the war broke out in 1870, and his diplomatic baiting with the Ems Dispatch, France declared war upon Prussia, making it seem the aggressor. That, and the part of French diplomats about "restoring France to its natural borders" to the Rhine river in the events leading up to the war, also did not help France's image as the victim, especially as the war turned decisively against them in the Siege of Metz (trapping 200,000 French troops), and the disastrous Battle of Sedan, which saw the capture and surrender of 120,000 French troops and the capture of their leader, Napoleon III.
Because of France's prior actions in the 1860s under Napoleon III's foreign policy, they alienated the Austrians by aiding the Italians in their Second War of Independence (1859), which saw the Austrians lose territory to the nascent and newly-unified Italians. Bismarck's diplomatic maneuvering kept Russia nominally friendly or at the very least neutral against Prussia when they went to war with Austria in 1866, which culminated in Austria's loss of influence with the other German minor states, opening up the path to unification under the "Little Germany" unification idea, which was Germany without Austria.
France's foreign policy also alienated Britain, in that their colonial conquests and foreign policy tended to be anti-Britannic, which was the traditional mode of thought for Franco-Briton enmity at the time, and has existed for centuries up until that point. After Prussia's victories in 1866, and Bismarck's vague promises of compensating Napoleon III for guaranteeing French neutrality while the Prussians curbstomped the Austrians, France saw itself somewhat swindled by the current state of affairs in the period between 1866-1870 - suddenly, to their east, was a large country that was more politically unified than ever before, and worse, had a professional military with reserves that they can mobilize that can outnumber their men in the field.
Compound this strategic reversal on the map of Europe was the fact that France had very little to count on from the other European powers:
Britain was cold towards France as was the usual case. France was seen as the "biggest threat" to Britain, and despite their cooperation against Russia in the Crimean War, there were a series of naval arms races between the two countries that made relations cold.
Russia was not friendly towards France because of the latter's involvement in the Crimean War, easily within living memory of the statesmen of the time, not to mention Napoleon III was seen as one of the arch-architects of organizers of the coalition against Russia during that war.
Austria certainly could not be counted on due to their recent reorganization in having to make political concessions to their Hungarian counterparts after the disastrous war of 1866 left the Austrians militarily and politically impotent during the 1870 war.
The United States was not going to be involved, they just emerged from their Civil War in 1865, and not to mention they were not in any power to mount any kind of military expedition in the aid of France.
Italy might have been the only state that could have helped France, but they were also recently unified and consolidating. However, France was still guaranteeing the security of the Pope in Rome, and Italian nationalists yearned to make Rome their capital. When the war broke out, the French withdrew their Roman garrison to reinforce the mainland, and the Italians promptly occupied Rome. However, there were Italians who did not forget France's part in aiding the Italian unification efforts of 1850-1860s, and there were those who joined on the side of France during the war, such as the Italian patriot Giuseppe Garibaldi, who led a volunteer force to aid the French.
Spain did what it did best in the Nineteenth Century - which was to stay neutral of Continental European affairs in a large part.
The Prussians understood that the war had to be kept short and the overall strategic objective was to secure German unification, and that meant defeating France, whose interests were not served by a strong, unified Germany, which would replace France as the pre-eminent European land power. Bismarck himself even said he did not want Germany to annex the French provinces of Alsace and Lorraine, judging (correctly) that this would lead to a permanent enmity with France, but the German nationalists and German military leaders won that debate in arguing that Alsace-Lorraine was populated by ethnic Germans, and the military leaders arguing that they wanted a strategic buffer on their western frontier controlled directly by the central government in Berlin. This enmity between France and Germany would be one of the culminating causes of World War One, and Bismarck's diplomatic policies of keeping France diplomatically isolated ended with his dismissal in 1890, with Kaiser Wilhelm II's "zig-zag" foreign policy achieving relative diplomatic isolation on the part of Germany when France and Russia formally concluded a military alliance in 1892, thus surrounding Germany with potentially hostile powers on two fronts - something Bismarck feared the most, and had come to pass.
TLDR; brilliant diplomatic maneuvering on the part of Bismarck and alienating French foreign policy by Napoleon III in the years leading up the the 1870 war left the French diplomatically isolated and effectively gave the Prussians a free hand in defeating the French.