"We have put in place a code of conduct that prohibits alcohol," Mr Hao'uli told 1News..
"Unfortunately by law we cannot make it illegal for people to drink."
Tonga has previously sent workers back for behaviour such as drunkenness and Fiji also recently banned four villages from taking part in it for a period for bad behaviour by some workers.
The scheme has run since 2007 and the remittances the workers send back to the islands are important for their economies.
English said there was concern about the actions of a particular group of workers and Pohiva had apologised for it out of concern for the reputation of Tonga.
"The Prime Minister made it clear they were tightening up the screening to try and get what he described as the right people going to New Zealand."
Pohiva said it had created some "uneasiness" in the relationship with New Zealand, but English downplayed that.
"We want to make sure New Zealanders don't feel threatened by bad behaviour by RSE workers and Tonga is quite sensitive about its reputation in New Zealand."
"Everyone wants the right thing to happen here, it's just a matter of how you can pick the right people and supervise them in a way that means everyone is happy with how it goes."
He said the oversight of the workers while they were in New Zealand was also important.
"These are larger groups of younger men and there needs to be quite a lot of supervision to be sure that they behave in a way that the Tongan Government regard as appropriate for the reputation of Tonga."
However, he said about 10,000 workers came to New Zealand each year and "overwhelmingly they make a good contribution."
He said the Prime Ministers of both Samoa and Tonga had taken a close personal interest in the scheme and undertaken to do what they could.
"That's not a guarantee every one of them will behave perfectly, but I'm sure they're doing all they can to reduce the opportunities."
George Rarere, Immigration NZ's manager of Pacifica Labour and Skills, said it did not send back RSE workers for simple bad behaviour, but since 2010 a total of 52 had been deported for breaching visa conditions or criminal activity.
Tonga has been involved in the RSE scheme since it began in 2007. A pilot study of Tongan and Samoan workers last year found on average Samoan workers sent back remittances of $4,614 each - about $5.8 million all up. Tongans sent back $5525 - worth $8.6 million to the economy.
Surveys of employers taking part, such as orchardists and vineyards, have shown strong levels of satisfaction with the workers, other than some isolated cases of bad behaviour.
Most employers ranked the RSE workers as harder working and more disciplined than the workers they employed locally or through Work and Income.
Australia has now started a similar scheme after seeing the success of New Zealand's.
English followed up his meeting with Pohiva by visiting Tonga's King at the Palace. He is on the final leg of his Pacific Mission to the Cook Islands, Niue, and Tonga.
That winds up tonight at a reception where the entertainment will be the double feature of the Tonga-Wales and Samoa All Blacks rugby games.
