What tantrum? The time to buy EM currencies may be now

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Markets may be bracing for another tantrum across emerging markets as the U.S. Federal Reserve edges closer to its first rate hike in nine years, but some players say now is the time to swoop up those countries' currencies.

"There's a valuation signal there that's quite strong," Julien Seetharamdoo, chief investment strategist at HSBC Global Asset Management, said earlier this week. "Some of those currencies should strengthen in the medium to long term," he said, noting a preference for Asian emerging markets with supportive macro fundamentals.

He's positive on South Korea's won, India's rupee and the Malaysian ringgit.

Read More Why the Fed just sent the dollar lower

That runs counter to market concerns that higher interest rates in the U.S. will spur outflows from emerging market (EM) assets as higher yields on U.S. Treasurys, considered a "safe" asset, makes riskier assets appear less attractive.

Similar concerns spurred a broad rout, dubbed the "taper tantrum," across emerging market assets in mid-2013 after then-Fed chief Ben Bernanke surprised markets by first broaching a plan for the U.S. central bank to begin tapering the asset purchases under its quantitative easing program.

But Seetharamdoo noted that while other assets, such as fixed income, stabilized after the taper tantrum, EM currencies have now sold off for more than two years. , for one, has lost nearly 23 percent of its value against the U.S. dollar since the beginning of 2013.

He did, however, caution that it's not a short-term play.

"It's difficult to time these markets perfectly," he said. "There's definite risk of more volatility and more weakness in the short term," especially as the Fed raises interest rates.

The Fed on Wednesday left rates unchanged after its two-day meeting, but it did provide a statement and forecasts that suggest it could raise rates once, if not twice, this year should it see improvement in economic data, including inflation.

Seetharamdoo isn't alone in not expecting another major tantrum.

Read More Are Asia's markets facing a 'hike hissy'?

"Most EM currencies now appear undervalued against the dollar, which is quite different to the situation that prevailed two years ago," David Rees, senior markets economist at Capital Economics, said in a note Tuesday. "While we think that Fed lift-off will probably lead to some further dollar strength in the months ahead, on the whole we expect additional depreciation of EM currencies to be limited."

To be sure, Rees isn't expecting EM currencies to rally, just not fall much more. Others also aren't terribly keen about EM assets.

"[It's] still too soon to get excited," Amundi, which has 950 billion euros ($1.08 trillion) under management, said in its June strategy note. It's neutral on EM currencies, citing in part a concern that China's efforts to use monetary easing to stimulate its economy hasn't been sufficient to help industrial commodities, which in turn has weakened many other emerging economies.

Some think the dollar is only heading higher, even though the greenback actually weakened Wednesday after the Fed meeting.

"While the market was disappointed by the Fed, in no way shape or form do we believe that the long trade is dead," Kathy Lien, managing director at BK Asset Management, said in a note Thursday. She said BK is using the pullback to add to its positions.

"The bottom line is that U.S. rates are rising this year," she said, noting there could even be two 25 basis point hikes this year. "In an environment where the Reserve Bank of Australia, the Reserve Bank of New Zealand and the European Central Bank are either easing or talking about doing so, the dollar will remain attractive."

--Patti Domm contributed to this article.

—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1