But Rajapaksa, who is in for a tough contest to retain power, conceded that some changes could be made.
"I believe the current executive presidency needs changes, but its total abolition could lead to political instability in the country," Rajapaksa was quoted as saying by the Bottom Line Newspaper.
On opting for a Westminster model, Rajapaksa said in a lighter vein that if anyone is serious about such a constitutional change, it should be he himself because he is now seeking the second and final term.
When asked whether he would do away with executive presidency if elected for the second term, he said no one would be more interested than him in abolishing it.
His remarks come as the country's Election Commission is in the process of notifying the dates for the Presidential polls expected to be held early next year.
Media reports indicate that the elections could be held after the second week of January.
The President said that post-independent Sri Lanka in its early period witnessed frequent collapse of governments and the executive Presidency has corrected that situation and given the country some degree of political stability.
Rajapaska made these comments in his first interaction with the media after declaring snap polls.
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