The Auckland Tennis centre was evacuated on Tuesday after a security scare over an unattended bag.
The bag was found while a protest against Israeli player Shahar Peer was taking place outside the venue hosting the WTA Tour's Auckland Classic.
A tournament spokesman said the centre was evacuated at about 1040 (2140 GMT) before the bomb squad carried out a search.
"It was an unattended bag, it could have been somebody who went off and got a coffee and left it there," the spokesman told Reuters.
"As far as we know it wasn't anything that looked harmful. Obviously on a day like this, with an Israeli playing, it had to be reported.
"They put through the squad ... they did a sweep through and it has been done and let everyone back in (at about 1110)."
Play had been due to get underway at 1100.
The unseeded Peer was due to play Slovenia's Polona Hercog in the first match on Court Four.
The New Zealand Press Association reported that about 20 protesters had been outside the venue protesting against Peer's presence in the tournament.
