Snap may have climbed close to its original highs on Monday after several firms initiated coverage of the stock, but Jim Cramer remains hesitant for one big reason: discipline.

While Cramer doesn't discount the positive factors fueling Snap's new "buy" ratings, namely its target demographic, strong sales projections and innovative spirit, he worries that the stock is still too overvalued for its hype.

"If you're buying Snap here, you're paying 28 times this year's sales and 14 times next year's sales for the stock, and I just can't do it," the "Mad Money" host said.

Goldman Sachs was one of six firms to give the Snapchat parent a "buy" rating, calling Snap a "premium creative platform" that offers "higher reward potential" than its competitors, even if that goes hand-in-hand with a higher risk profile.

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"Snap's got massive growth, with its sales perhaps ready to double, and analysts can't resist recommending a stock with that kind of growth," Cramer said.

Advertisers are jumping at the chance to promote their products to the app's 158 million daily average users, many of whom are in their late teens and early twenties.

It's no wonder analysts like RBC Capital Markets' Mark Mahaney are expecting the company to multiply its average per-user revenues, which are currently at one seventh of Facebook's, at $1.05, Cramer said.

But even as firms like Jefferies recommend buying the disappearing messaging app's parent because they "believe Snap has all the ingredients to build a robust advertising business," Cramer thinks the opportunity is still too good to be true.

"Facebook trades at under 11 times 2017 sales and just 8.5 times next year's number. Alphabet's at 5.4 times 2017 sales and 4.7 times next year's revenue. Both companies are wildly profitable, while Snap's projecting gigantic losses for as far as the eye can see," he argued.

In addition, Snap's shareholders have no voting power, Facebook is aggressively competing with Snap using Instagram stories, and Snap pays Alphabet $400 million a year to host its app on the Google Cloud.

"I get it," Cramer said. "This is the year that all advertising firms are sampling Snap, so when you see the sales numbers they'll be humongous, no doubt more than the current estimates of even the stock's biggest supporters."

And he has no doubt the company will continue innovating, making its proponents even more excited with every new development.

"Discipline can be a real buzzkill at the beginning, but it's saved my bacon too often for me to ignore it. So I say enjoy Snap. Let it go higher all you want, but you'll be enjoying it without me," Cramer said.

Disclosure: CNBC parent NBCUniversal is an investor in Snap.

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