Prime Minister John Key said if the hotel lodged a complaint it would be "a very serious issue". He accepted Mr Gilmore's assurance that he did not invoke the Prime Minister's office, despite Mr Riches' statement claiming that he did.
Since the incident last week, further claims have surfaced about Mr Gilmore's behaviour, including allegations he acted in a sleazy manner towards women at his table.
Mr Gilmore has also been accused of bullying tenants of a house in the South Island village of Ohau that he helped manage through a trust.
Tenants Jane and Craig Ovenden told the Herald on Sunday that Mr Gilmore had used his status as an MP to intimidate them.
The Ovendens also said Mr Gilmore threatened to tell other landlords they were poor tenants, despite previously saying they were not, recorded conversations without telling them, and called their lawyer a "fool" in an email.
Mr Gilmore did not answers calls or emails yesterday.
His visit to Hanmer Springs last week was for the National Party's Mainland region conference, and he went to the Heritage restaurant for dinner with his partner and friends.
He has apologised on his Facebook and Twitter accounts - which are now closed - for his misbehaviour.
But a further public apology was criticised by Mr Riches because it said the entire group at his table had been "boisterous". Mr Riches said Mr Gilmore's apology was half-hearted and had shifted responsibility on to other people. The lawyer also left a note of apology at the restaurant and reassured the waiter Mr Gilmore did not have the power to have him sacked.
Mr Gilmore first entered Parliament as a list MP in 2008 but was not re-elected in 2011. He returned to the House two months ago, replacing former Speaker Lockwood Smith, who left to become New Zealand High Commissioner in London.
Mr Key does not have the power to remove Mr Gilmore from Parliament but the MP could be expelled from National's caucus.
Mr Gilmore could be penalised at the next general election by getting a lower placement on the National Party list. He is currently number 54.