The Trump administration may be reassured by the trend in recent years for growth figures to be depressed in the first quarter, but then pick up later in the year.
"US GDP figures are typically weaker in the first quarter, so this reading is in line with the seasonal trend," said Nancy Curtin, chief investment officer at Close Brothers Asset Management.
"We haven't yet had the expected fiscal stimulus from Trump, the effects of which may not be seen until the end of this year or the start of 2018."
The annualised first quarter growth rate of 0.7% was less than the 1% analysts had been expecting, and a slowdown from the 2.1% growth rate seen in the final quarter of last year
The slowdown was down to stagnant consumer spending, economists said.
"Household spending was held down by a drop back in motor vehicle sales from a near-record high at the end of last year and the unseasonably warm winter weather, which depressed utilities spending," said Paul Ashworth, chief US economist at Capital Economics.
But he thinks consumer spending will "rebound" as personal income showed healthy growth and data suggests that consumer confidence remains high.
Close Brothers' Ms Curtin also pointed out that other data suggested strength in the US economy .
"While investors might be disappointed with the reading, it has been a steady start to the year with inflation looking benign, a resilient jobs market and positive PMI [purchasing managers'] data."