Apple had forecast revenue of $63 billion to $67 billion for the second quarter to March.
US tech giant Apple said on Monday that disruption due to the novel coronavirus had hit both production and demand in China, and the company was "experiencing a slower return to normal conditions" than planned.
"We do not expect to meet the revenue guidance we provided for the March quarter," it said in a statement, adding that worldwide iPhone supply would be "temporarily constrained" and demand in China had been affected.
The COVID-19 virus death toll exceeds 1,850 in China, where it has infected more than 74,000 after emerging in the central province of Hubei.
Elsewhere, hundreds more have been infected and the virus has sparked panic buying, economic jitters as well as the cancellation of high-profile sporting and cultural events.
IMF chief Kristalina Georgieva said there could be a cut of around 0.1-0.2 percentage points to global growth but stressed there was much uncertainty about the virus's economic impact.
Apple said that "while our iPhone manufacturing partner sites are located outside the Hubei province — and while all of these facilities have reopened — they are ramping up more slowly than we had anticipated.
"All of our stores in China and many of our partner stores have been closed," it added.
"Additionally, stores that are open have been operating at reduced hours and with very low customer traffic. We are gradually reopening our retail stores and will continue to do so as steadily and safely as we can."
New cases outside the epicentre region have been declining for the last 13 days. There were 115 fresh cases outside Hubei announced on Monday — sharply down from nearly 450 a week ago.
Chinese authorities have pointed to the slowing rise in cases as proof their measures are working, although the World Health Organization's chief said the apparent drop in new cases "must be interpreted very cautiously".