"It was raised at the end of last year to low, and it's always under review because that's what the security organisations are there to do and until now at least there didn't seem to be a reason to raise that security threat level but no doubt that's going to be discussed extensively over the next few weeks.
The business of beating Isis was very "messy and unpredictable", Mr English said.
He said people would have to wait and see whether the France attack would strengthen the resolve of New Zealanders in the fight against Isis.
"It's a very difficult threat to deal with...These people are a threat to New Zealanders anywhere, not just in New Zealand.
"There's no indication that it's becoming more likely. We would get concerned if and when there's more activity in Australia. We certainly hope there isn't."
The death toll from the Paris terror attacks has risen to 132, after three people died in hospital, Agence France-Presse reported.
'An organisation with global ambitions'
Otago University international relations expert Robert Patman told TV3's Paul Henry programme he was "not totally surprised" the attacks had taken place.
Isis had been clear that it was extending its operations and targeting countries like France since last year, he said.
"This is an organisation with global ambitions," Mr Patman said.
"It basically has declared war. It declares war on non-believers and either kills them or enslaves them. And this is the way it behaves in the territory that it has under its control and it has 6 million people under its control, so we shouldn't have any illusions about that," he said.
Mr Patman said Isis was a political challenge as well as a military one.
The Islamic Council of New Zealand says it "strongly condemn the cowardly attacks on innocent French and Lebanese citizens that have shook the world in the last few days".
"As followers of the Islamic faith, we find it repugnant and counter to all universal human values to shed innocent blood in such a brazen and despicable way," Dr Nasser Abdul Monim said in a statement.
"No true divine faith teaches violence, and we denounce any individual and group that use such tactics to instil and reap terror within societies and disturb the routine of normal, functional lives.
"As expressed to the Minister of Ethnic Affairs, ICONZ is ready and able to cooperate with the Government at national and local level to counter the terrorism at grass root level by the eradication of religious illiteracy."