Prime Minister Ranil Wickremesinghe's minority government received only 31 votes while 52 voted against the motion to raise Sri Lanka's treasury bond limit by over USD 3 billion.
The defeat has exposed Sirisena-Wickremesinghe government's vulnerability ahead of this week's move to adopt the 19th amendment to the constitution.
Sirisena is on an official visit to Pakistan.
The 19th amendment which aims to reduce presidential powers was a major reformist pledge of Sirisena in the presidential election held in January.
Commenting on the parliamentary outcome on the motion Dinesh Gunawardena, the senior opposition leader, demanded resignation of the Wickremesinghe government.
"How can the government carry on when they are unable to get parliamentary approval for financial regulations," Gunawardena said.
