Acevo has called on the Department for Digital, Culture, Media and Sport to remove a clause banning charities from using Tampon Tax Fund grants for advocacy and awareness raising.
But a spokeswoman for the DCMS - which is the parent department for charities and civil society - said it was opposed to taxpayers' money being used for campaigning.
The Tampon Tax Fund gives away money raised from VAT on tampons, and the government has recently opened applications for £15m, administered by the Office for Civil Society within DCMS.
Grants of at least £1m are available for charities that support mental health and wellbeing and tackle violence against women and girls, as well as for projects that aim to reduce drug and alcohol abuse and engage excluded and vulnerable women through sport.
In the fund's guidance for applicants the government includes a long list of things that grants cannot be spent on. These include “advocacy”, “appeals”, and “campaigning and awareness raising”.
The clause was also included in last year’s guidance for the Tampon Tax fund.
This clause - known as the "gagging clause" was introduced by government last year. Charities campaigned widely against its wider introduction.
Vicky Browning, chief executive of Acevo, today called on the DCMS to remove the clause which excludes the money being used to fund campaigning to be removed to “enable successful grantees to have maximum impact with the funds they are awarded”.
Browning said that one part of the guidance told charities that they should follow the strategy to prevent violence against women and girls, known as VAWG, and says that one way they should do this is through awareness raising.
But another part of the guidance banned awareness raising.
She said: “This grant specification demonstrates a contradiction at the heart of this government's view of the value of civil society - offering funding to tackle the huge problem of violence against women, specifically including raising awareness, while at the same time explicitly ruling out campaigning and raising awareness as a use for the funding.
“It sends a conflicting message to those charities that simultaneously deliver services and raise awareness, both of which are vital to organisations tackling violence against women.
“We call for this clause to be removed to enable successful grantees to have maximum impact with the funds they are awarded.”
'Taxpayers' money should not be used for campaigning'
But a spokeswoman for DCMS said the department was opposed to money being used for campaigning.
"We are committed to ensuring that taxpayers’ money goes to help good causes and is not used for political lobbying and campaigning," she said. "The money generated from the sale of sanitary products is used to help disadvantaged women and girls directly. The fund is already making a real difference to women's lives, addressing serious issues that they face and supporting organisations across the country."
She said the government had included a line encouraging awareness raising by mistake, and that this line would be removed.