His made the statement in response to an ultimatum delivered to the government by a group of protesters in Nakhon Si Thammarat on Tuesday.
The group demanded the promised subsidy _ 2,520 baht per rai of farmland capped at 25 rai per farmer _ be put in writing.
It said the government must send a representative to sign a subsidy agreement in Nakhon Si Thammarat by tomorrow or face mass protests on Saturday.
Amnuay Yutitham, core protest leader in 16 southern provinces, said the subsidy must also be distributed equally to all farmers, including those who do not hold ownership papers for their land.
The government must also vow not to prosecute core leaders and farmers for staging the recent protests, he said.
The cabinet on Tuesday endorsed the national rubber policy committee's proposal to double the subsidy for rubber farmers to 2,520 baht per rai.
Eligible farmers must have land ownership papers and would be subsidised for a maximum of 25 rai each.
Pol Gen Pracha said deputy secretary to the prime minister Thawach Boonfueang will meet the protesters on Saturday morning but will not sign any deal with them.
He believed all issues could be resolved through negotiation.
The deputy premier, however, said those who committed criminal offences during the protests would not be spared charges.
Pol Maj Gen Thawach said he would meet relevant authorities next week to decide what legal actions would be pursued.
He said he had no idea at this stage how many cases local authorities were investigating in connection with the rubber protests.
PM's Office deputy spokeswoman Sunisa Lertpakawat said Pol Gen Pracha had appointed three sub-committees to handle the rubber protest issues.
The first panel, headed by Pol Maj Gen Thawach, deals with criminal cases; the second panel is being chaired by Deputy Agriculture Cooperatives Minister Varathep Rattanakorn and deals with public relations; and the third covers land ownership issues with Deputy Prime Minister Yukol Limlaemthong in charge.
In Prachuap Khiri Khan yesterday, core Bang Saphan district rubber protest leader Santhat Dechkerd said farmers in the district were disappointed with the outcome of Tuesday's meeting of farmer representatives in 14 southern provinces.
At the meeting, 18 rubber farmer representatives accepted the national rubber policy committee's subsidy offer, while the other 18 representatives voted against it, Mr Santhat said.
The meeting's chairman cast the deciding vote in favour of the subsidy offer, he said.
But Bang Saphan rubber farmers rejected the decision, which went against the farmers' intention to fight for price intervention, not a subsidy, Mr Santhat said.
Surat Thani protest coordinator Manoon Upala said even though rubber growers in the province were split over the offer, they have decided to suspend protests for 60 days to allow the government to turn its promise into action.