Singapore had previously barred 27 invited activists from attending the gatherings, citing "security and law and order" concerns for the move.
But late on Friday, Singapore reversed its decision, saying it would allow 22 of the 27 blacklisted activists into the country in an apparent effort to diffuse tension with the two institutions.
The Singaporean government said if the remaining five activists attempted to enter the country, they would be interviewed and may not be allowed in. The statement did not identify any of the individuals.
"Enormous damage has been done and a lot of that damage is done to Singapore and self-inflicted,” Wolfowitz said on Friday in response to questions from civil society organisations at a meeting in Singapore.
"I would argue whether it has to be as authoritarian as it has been and I would certainly argue that at the stage of success they have reached, they would do much better for themselves with a more visionary approach to the process."
Non-governmental organisations are set to boycott the financial institutions annual meetings in protest at the rigid security measures in the city-state.
The environmental group Friends of the Earth International said that "80 social, environmental and small farmers organisations" would join them in boycotting the meetings.
The campaigners had been invited to attend as part of an effort by the IMF and World Bank to engage with their critics.
Singapore has also banned outdoor demonstrations during the meetings saying they could lead to violence.
Hundreds of activists gathered on the nearby Indonesian island of Batam to protest against the ban.
Some activists said Singapore's move to reverse its decision came too late.
Several official activities organized for such groups had already started this week and some of the blacklisted individuals had canceled their travel plans.
"Expensive travel plans have already been undone, and many civil society organizations are unable to fly to Singapore on a moment's notice," said Romilly Greenhill, a senior policy analyst at the South Africa-based ActionAid International.