It's unclear if you mean whether it was (1) a ruse by Wilson against the American public, or (2) Germany against the USA, or (3) Germany against Mexico, or (4) British against USA?
As far as being a ruse by Wilson (e.g. he made up the telegram to present to Congress), this can likely be discounted since there is documentary evidence - in 2005, an original typescript of the deciphered telegram (with Blinker Hall's handwriting) was discovered in UK.
Also, as noted below, Zimmerman himself admitted to sending it.
As far as Germany's ruse against the USA, it was most definitely not a ruse. It would have had (as it did) an obviously opposite effect of what Germany wanted had it been intercepted - e.g. USA entering the war against Germany on the side of Entente.
In addition, on March 29, 1917, Zimmermann gave a speech in which he admitted the telegram was genuine. (src: Meyer, Michael C. "The Mexican-German Conspiracy of 1915", The Americas. 23.1 (1966): 76)
As far as German ruse against Mexico (in other words, bait them with German help to attack the USA but know all along that you can't provide enough help) - it is certainly plausible, but impossible to ascertain.
On one hand, that was definitely in German interests, since they were worried that USA would declare war on Germany over unrestrained submarine warfare announcement that was forthcoming.
On the other hand, Germany had plausible reasons to believe that Mexico might be successful.
The failure of the Americans under General John J. Pershing to capture Pancho Villa in 1916, in the movement of President Carranza in favor of Germany emboldened the Germans to write the Zimmerman note (Wiki source: Friedrich Katz, The Secret War in Mexico: Europe, the United States, and the Mexican Revolution (1984) pp 346-7)
British ruse against Germany - it wasn't the first attempt to ally with Mexico. From Wiki:
The Telegram was not an isolated case of German-Mexican collaboration, for Germany had long sought to incite a war between Mexico and the U.S., which would have tied down American forces and slowed the export of American arms to the Allies. (src: Friedrich Katz, The Secret War in Mexico: Europe, the United States, and the Mexican Revolution (1984) pp 328-9
The Germans had engaged in a pattern of actively arming, funding and advising the Mexicans, as shown by the 1914 SS Ypiranga arms-shipping incident *(Katz, The Secret War in Mexico pp 232-40) and German advisors present during the 1918 Battle of Ambos Nogales. The German Naval Intelligence officer Franz von Rintelen had attempted to incite a war between Mexico and the U.S. in 1915, giving Victoriano Huerta $12 million. (Katz, 329-32)
The German saboteur Lothar Witzke, responsible for the March 1917 munitions explosion at the Mare Island Naval Shipyard in the Bay Area, and possibly responsible for the July 1916 Black Tom explosion in New Jersey, was based in Mexico City. (src: Priscilla Mary Roberts, World War One p. 1606)