The dollar recovered on Friday from its declines the previous day on the back of solid U.S. growth figures, while the Swiss franc fell sharply on market jitters of suspected intervention.
Traders said the market was nervous about intervention by or on behalf of the Swiss National Bank to keep the franc's strength in check because the euro had fallen to levels around 1.5080 francs where the SNB had already intervened this year.
The Swiss National Bank declined to comment.
The euro held above a 2-1/2-week low against the dollar after it rose on Thursday, when data showing the U.S. economy grew for the first time in more than a year had raised optimism about the global economic recovery and stoked risk appetite.
European shares failed to add significantly to its rally from the previous day, suggesting that some of the initial euphoria from the U.S. figures may have fizzled, while U.S. stock futures fell 0.4 percent.
Currencies seen as being higher-risk struggled to make headway as stocks posted limited gains, while the yen also erased some of the previous day's falls.
"The market is waiting to see if the rise in risk appetite is durable," said Jeremy Stretch, strategist at Rabobank in London.
"The recovery is continuing, but there are enough question marks to keep the market worried," he said, adding that a comatose job market and the wind down of the "cash for clunkers" scheme raised questions about whether U.S. growth will continue.