"That hasn't really worked in parliament and I'm not sure it will work in the country", she said.
May triggered a two-year countdown to Britain's exit from the European Union last month, and high-stakes negotiations to settle divorce terms and agree on a new relationship are expected to start within weeks.
Analysts at ETX Capital say in a note to clients that the election call "adds another layer of complexity to an already uncertain picture for United Kingdom and European assets".
Leader of the Liberal Democrats, the second-largest opposition party in Britain, also said he looked forward to fighting the parliamentary election. Political divisions "risk our ability to make a success of Brexit", she said.
"What we are doing is not voting for a new prime minister for just two years over Brexit, but for a new prime minister for a duration of a parliament of five years", he told the Commons.
Britain voted in July last year to leave the union after 44 years of membership in a divisive and hotly contested referendum.
The leader of the main opposition Labour Party, Jeremy Corbyn, said Tuesday he backed the call.
Ms May pledged several times after taking office previous year not to call an early election, so this is something of a U-turn.
In calling for an early general election in June, the Prime Minister is showing an unexpected gambler's streak, said Charles Pattie, a professor of electoral geography at the University of Sheffield.
Our opponents believe that because the Government's majority is so small, that our resolve will weaken and that they can force us to change course.
The leader of Ukip, Paul Nuttall, said that every vote for Ukip "will be a reminder to the PM that the British people want a clean Brexit with restored borders".
In another twist, Downing Street's director of communications, Katie Perrior, quit: "Always said I wouldn't stay past an election".
"A commitment to no early general election dismissed as easily as parts of the recent Budget".
In a surprise statement outside Downing street, the prime minister said: "After the country voted to leave the EU, Britain needed certainty, stability and strong leadership".
Corbyn said he would not oppose the call for an election.
"It will be voted in favour of in the Commons tomorrow because they'll be forced into it in some extent".
"However, she has chosen to put party advantage before the good of the country".
Critics argued then that she should not be linking her government to Christian values while presiding over cuts to benefits, the NHS, schools and other public services, just as critics today will argue that her "reluctant" move was sheer opportunism rather than statesmanship.