No. Actually, yoga is for humans, and humans have practiced yoga for quite some time - some scholars say up to 5000 years. For much of that time, yoga was almost exclusively a male practice. This was primarily because yoga grew amidst India’s cultural, religious, and misogynistic norms – not because men were naturally more inclined to it.
Yoga, as we now generally conceive of it, has been in the West only for half a century or so. One of America’s first teachers was Indra Devi – female yoga teacher to some of Hollywood golden-age starlets of the 1950s and 60s. Tabloid coverage of Greta Garbo and Eva Gabor practicing yoga gave the American yoga female demographic a big head start. Now, the distribution of women and men practicing yoga today in the US is somewhere around 80-20, but that gap has been closing of late.
Often the images we see shape the context of what we are seeing. Yoga Journal is the most prominent yoga industry publication and can be found in airports, bookstores, libraries, and grocery stores. It's everywhere. But only 3 out of 52 magazine covers from 2000-2008 depicted males - all others had female models. Repeatedly seeing only a woman do something might mislead one to thinking yoga is "female activity".
Despite this, the masculinity-icons SuperBowl XLVIII champions Seattle Seahawks - from the lumbering linemen to the svelte safeties - attended weekly yoga classes to stretch and relax their bodies, and focus and center their minds.
Rock stars Adam Levine, Sting, Jon Bon Jovi, and Mick Jagger are using yoga to nurture thier health. Makes sense. Men have limbs and muscles that need stretching and strengthening too; and we all could use some relaxation and de-stressing time.