The quarterly study, by the Mauritius Chamber of Commerce and Industry, showed confidence at 79.6 points, down from 85.3 points in the previous quarter.
"More than two-thirds of captains of industry surveyed said they have noted a drop in demand during the current quarter," Renganaden Padayachy, economist at the chamber, told a news conference.
"Consumption behaviour is generally impacted in times of economic uncertainties as consumers tend to be more cautious."
Padayachy said there had been a decline in consumption growth in Mauritius from 6.5 percent on average over the period 2004-2008 to 2.5 percent on average over the period 2009-2013.
Last week, Statistics Mauritius trimmed its economic growth forecast for this year to 3.5 percent from an earlier estimate of 3.7 percent. It cited anticipated lower growth in the textile and information and communication sectors.
The economy expanded by 2.4 percent in the first quarter against 3.8 percent a year earlier.