Brigadier Ed Butler denied there were plans to tackle the insurgency with pre-emptive strikes on Monday as the 3,300-strong deployment arrived to take over from US troops and support reconstruction efforts in the area.
Butler said tribal conflicts in the province posed a greater threat than loyalists to the deposed Taliban government or Osama bin Laden's al-Qaeda.
"We are not going out to look for trouble," Butler told BBC radio.
While acknowledging "that Helmand is a less benign area than we have been in previously", he said his troops were prepared for the challenge.
Not about insurgency
"Most importantly, we are starting to understand the nature of the problem and the violence is not about the insurgency, it's not about the Taliban or al-Qaeda. It's more fundamental than that.
"It's about tribal issues, it's about water and land rights, it's about feudal and historical matters, and that's what we need to understand."
"The violence is not about the insurgency, it's not about the Taliban or al-Qaeda... It's about tribal issues, it's about water and land rights, it's about feudal and historical matters"
Brigadier Ed Butler, commander of British forces in Afghanistan
The extra British troops - tripling the 1,100 already stationed in Afghanistan as part of a multi-national operation working on counter-narcotics and reconstruction - will be part of the Nato-led International Security Assistance Force.
However, John Reid, the British defence secretary, had said last week that British troops could also stage offensive missions in Afghanistan.
On Tuesday, a car-bomber attacked Canadian troops travelling near the capital, killing himself and a passerby, a Canadian military spokesman said.
The blast on a main road to the northeast of Kabul, leading to the main US military base at Bagram, killed a man riding a horse beside the road, police said.
In Helmand on Saturday, Canadian forces had killed 15 to 20 insurgents carrying assault rifles and grenade launchers who were "moving with the intent to set up an ambush" in Sangin district, a military statement said on Monday. No coalition forces were hurt.
Helmand was also the scene of a bomb attack on Monday - one of four over a 24-hour period across the country that wounded two coalition soldiers and an Afghan boy, officials said.
The only people killed by the bombs were the four attackers. Two accomplices were also hurt.
The attacks targeted an Afghan army convoy in Grishk district in Helmand province, an American troop convoy in southern Kandahar province, a coalition convoy in Tirin Kot, the main town in the central Uruzgan province, and an unknown target in Matta Khan, a village about 150km southeast of the capital, Kabul.