The move comes after an intense power struggle in the past two weeks which followed Sirisena's sudden sacking of Prime Minister Ranil Wickremesinghe and the appointment of former leader Mahinda Rajapaksa.
The dissolution, which is expected to be challenged in court, was revealed in an official gazette notification signed by Sirisena which also set the next sitting of parliament for January 17.
The President dissolved the parliament in a gamble to pave the way for snap elections to secure a majority for his party in a new government when the President-led UPFA realized that they do not have a majority in the parliament and has not been able to get enough crossover legislators to support them.
Relations between Wickremesinghe and Sirisena became strained this year after their coalition was defeated in local elections by a Rajapaksa-backed party.
"Dissolving parliament at this time is illegal and goes against the constitution", JVP's general secretary, Tilvin Silva, told reporters.
Following the sacking, the president suspended parliament in a move which Wickremesinghe said was meant to prevent the ousted prime minister from contesting the decision in the legislature.
As protests rocked the streets of the capital Colombo, however, the United National Party voiced its indignation on social media, saying it "is illegal and goes against the constitution".More news: NASCAR Might Take Away Wins If Teams Keep Cheating Next Season
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"Unfortunately, we fear that recent actions, if not corrected, will threaten your country's democratic development and derail the progress made in recent years", said the letter to Sirisena.
Dayasiri Jayasekara, a cabinet minister, told Al Jazeera that Sirisena had no choice but to dissolve parliament because of Wickremesinghe's refusal to step down.
Parliament Speaker Karu Jayasuriya on Monday slammed Sirisena's "unconstitutional and undemocratic" actions to sack Prime Minister Wickremesinghe and suspend parliament, saying he will not recognise Rajapaksa as the new premier unless he wins a floor test. At least eight have switched sides, but at least 120 deputies in the 225-seat parliament remain loyal to Wickramasinghe.
The United States and the UK have raised concerns over the decision taken by President Maithripala Sirisena to dissolve Parliament.
The EU, in a joint statement with Norway and Switzerland, called for parliament to reconvene and hold an immediate vote.
Wickremesinghe late Thursday thanked his supporters and urged them not to give up. "For this inspiring effort, I want to thank everyone who has risen to fight for democracy and justice".