The charge followed a 2am incident at Coyote Bar and Restaurant in Hamilton on March 5, when the former All Black got into a fight with a patron while drinking at the bar.
The court was told Lauaki punched the victim at least twice, with one closed fist blow leaving him with cuts and bruises to the lips.
After his appearance today before community magistrate Rae Brooker, Lauaki spoke to news media outside court.
"I'm really disappointed that I let my family down, my mum and dad down and my team mates down," he said.
The incident occurred the week before the Chiefs lost to the Crusaders 19-26 in the Super 14 at Hamilton's Waikato Stadium.
There was a delay naming the side to play the Crusaders following the news of the assault charge, with Lauaki eventually omitted from the match.
He had just come off a two-match suspension for a spear tackle in the Super 14 match against the Lions in Johannesburg, where he captained the Chiefs in the absence of Mils Muliaina.
Chiefs' senior players Richard Kahui, Liam Messam, Brendon Leonard and Muliaina were there to support him at court.
The sixth-placed Chiefs fly to Australia this week to play the Brumbies in Canberra on Friday night.
Lauaki was to reappear for sentence on May 6.
Over the next six weeks, he has volunteered to complete an alcohol management course. He will also be taking part in New Zealand Rugby Union (NZRU) and Chiefs disciplinary processes.
After the incident Megan Mahaffey, manager of the Lone Star bar next to Coyote, said she felt sorry for Chiefs players "who are regularly picked at", especially by "young people looking to pick a fight".
Hospitality entrepreneur John Lawrenson, who co-owns six Hamilton inner-city bars, also believed Chiefs players were well behaved.
"I have owned many bars over the last few years and I can tell you I have never had one negative incident involving a Chiefs player," Mr Lawrenson said.
