Ugandan police have warned people planning to hoot car horns in protest at the rising cost of living they will face arrest for noise pollution.
The opposition call to honk horns or whistle five times at 1700 local time (1400 GMT) was to complement the "walk-to-work" protest begun in April.
A reporter says some honking could be heard at the appointed time, but it was rather low key in some areas.
Rights groups have criticized the violent crackdown on recent protests.
They say at least nine people have died, while the government accuses the opposition of trying to organize an Egypt-style uprising after losing an election in February.
Opposition leader Kizza Besigye says the vote was rigged.
Dr Besigye has been arrested four times and placed under preventative arrest once since the protests against the rising cost of food and fuel began.
Henry Bellingham, the UK's minister for Africa, called on President Yoweri Museveni to rise above "petty party politics".
He said the "very tough tactics" used against Dr Besigye were a concern for the UK government, one of Uganda's largest aid donors.
"President Museveni won with a big majority, he should now be magnanimous, he should be statesman-like, he should rise above trying to make any moves against the opposition," Mr Bellingham said.
"[He should] carry on the excellent work which he's doing in many ways in terms of the prosperity agenda in Uganda [and] counter-terrorism.
“On all these fronts Museveni has been doing a good job, but I think it demeans him and his government to use excessive force and these tactics against the opposition."
Mr Museveni was sworn in for a fourth term as president earlier this month.
He says he wants a new law to deny bail for six months to those arrested for rioting or causing economic sabotage.
May 23, 2011
Uganda Warning Over Horn-Honking Protest
We’re keeping a constant eye on Uganda. More to come of its dynamics with Somalia, but for now this report indicates the direction that Ugandan President Yoweri Museveni is heading: