Thousands of Bangladeshis have protested in the capital Dhaka at the visit this weekend of US Defence Secretary Donald Rumsfeld.
Hardline Islamic and left-wing groups had the same message
Some protesters burned American flags and chanted "Rumsfeld is a war criminal" and "Killer go home".
They believe Mr Rumsfeld will ask the country's leaders for Bangladeshi troops to be sent to Iraq.
The Bangladesh government still insists a UN mandate is required before it can consider sending peace-keeping troops.
Mr Rumsfeld is scheduled to stay in Dhaka for a few hours on Saturday as part of an Asian tour.
Left-wing and hardline Islamic groups held separate protests on Friday but the message was the same.
Mr Rumsfeld has said he will not press nations for troops
Hemayet Uddin, of the Islamic Constitution Movement, told a rally after Friday prayers:
"Facing stiff resistance in Iraq, Rumsfeld is coming to Bangladesh to collect soldiers to fight for them. Bangladesh cannot be a part of American barbarism in Iraq."
At a left-wing rally, Muzahidul Islam of the Communist Party of Bangladesh, said:
"Bangladesh can send troops to Iraq only to dislodge the Americans from the Middle East."
The country's foreign office said Mr Rumsfeld would hold talks on bilateral and international issues with Prime Minister Begum Khaleda Zia and Foreign Minister Morshed Khan.
'No combat role'
Mr Rumsfeld has told reporters on his tour he will not press nations for
However, the protesters and some Bangladeshi officials believe he may urge the Muslim-majority nation to send troops to help the new Iraqi government when it takes over on 30 June.
"We have repeatedly said that our position is very clear," said Mr Khan.
"We never participated in any peacekeeping mission that could entail fighting for or against any side."
He said no step would be taken "outside the UN".
Tight security will be in place for Mr Rumsfeld's brief visit.