Police spokesman Col Anton Bahrul Alam said the two organisers were from a promotional company in Jakarta.
The girls were crushed on Sunday when an estimated 3,000 fans turned up at a record store in Jakarta's Taman Anggrek shopping mall to see the group.
Police spokesman Col Anton Bahrul Alam said the two organisers were from a promotional company in Jakarta.
He said further charges might also be filed against other people involved in Sunday's event.
The four members of A1, who were on a tour of Asia, have said they are "devastated" by the tragedy.
They are on their way back to the UK after cancelling the rest of their tour, missing a press conference about the incident.
A spokesman for the group said: "They (A1) have cancelled the rest of the tour and their thoughts are with the families and friends of those killed and injured."
Security guards at the shopping mall said panic broke out when fans tried to escape the crush by rushing to the mall's exits.
A hospital official said the four girls had died after falling during the stampede.
Two others are in a critical condition in hospital.
Precautions
In the Philippines, the band was forced to cancel an appearance at a music store after some 20,000 fans turned up instead of an expected 1,000.
But Sony Music, the band's record label in Indonesia, defended the organisers of Sunday's event.
They said they thought adequate precautions had been taken to control the crowd, which had been much larger than expected.
"Before the arrival of the group, there were only about 1,000 fans there and things were very much under control," said a Sony spokesman.
"But as soon as they started signing autographs in a matter of minutes (the crowd) multiplied so that there ended up about 3,000.
"When they realised it, within 10 minutes only, the band was evacuated."
A1 is made up of singers Mark Read, Ben Adams, Christian Ingebrigtsen and Paul Marazzi, aged between 20 and 25.
They last year had a UK number one with a cover of the 1980s A-ha hit Take On Me and won Best Newcomers at the Brits.
TV appearance
Sony also defended the group's decision not to attend the press conference.
The spokesman said they had been unable to attend in person because "they are still very, very young" and the tragedy was "beyond their comprehension".
He also defended their live appearance on a local TV station after the tragedy, saying they only learned about the deaths several hours later.
Foreign pop groups rarely visit Indonesia, which is suffering from serious social and economic problems.