Foxconn said revenue last month reached $14 billion, in line with the company's own expectations.
For smart consumer electronics products, which include smartphones and are the company's main business driver, revenue in April declined as it entered the "traditional slow season", the company said in a statement, without elaborating.
Business in the second quarter is expected to decline due to a high base last year and "the seasonal off-peak period" amid a transition between old and new products, it said.
The first half of the year is traditionally slower for Taiwan tech manufacturers as major electronics vendors launch new products near the year-end holiday season.
Foxconn will report first quarter earnings on May 11 when it will also give an update on its outlook for the full year.
The company in March predicted revenue for the full year to be flat, with weak demand for consumer electronics offset by growth in computing, cloud, networking and component products.
Foxconn shares have risen 5.1 per cent so far this year, lagging the broader Taiwan market which is up 10.5 per cent.