Finance Minister Ravi Karunanayake however told Reuters after market hours that he believed interest rates should fall following the central bank decision to float the rupee currency on Friday.
The currency fell 3 percent to hit a record low of 139.00 against the dollar.
The main stock index ended 0.42 percent lower, or 30.39 points weaker, at 7,215.11, its lowest close since July 23. The index fell 1.8 percent on the week, its third straight weekly decline.
"Today's equities wrapped up in red in lacklustre trade. Investors are waiting till proper economic reforms are put forward," SC Securities (Pvt) Ltd said in a note to investors.
"Volatility in global equities persisted and the emerging currencies weakened, as investors exited before U.S payrolls data on Friday."
Analysts said the central bank's move to float the rupee also put investors on a wait-and-see mode.
Foreign investors bought 190.4 million rupees ($1.38 million) worth of shares on Friday, but they have sold a net 3.49 billion rupees so far this year.
Turnover stood at 540.1 million rupees, around half of this year's daily average of 1.15 billion rupees.
Shares in Ceylon Tobacco Company Plc fell 1.89 percent, dragging the index down.
($1 = 137.5000 Sri Lankan rupees)
(Reporting by Ranga Sirilal and Shihar Aneez; Editing by Biju Dwarakanath)