The RNLI has advised its staff and volunteers to choose carefully when to wear its uniform after what it described as "unacceptable abuse" endured in recent weeks.
On Sunday an RNLI boat carrying more than 100 migrants was denied access to the Port of Southampton and the Port of Portsmouth.
Associated British Ports (ABP), which operates Southampton, said there was not a "safety of life at sea issue where Southampton was the closest port", and reports have said the King's Harbour Master (KHM) Portsmouth declined a coastguard request.
Digital Secretary Lisa Nandy earlier on Tuesday said she was "personally concerned" about social media doxxing of volunteers - when a person's private information is shared online without their consent.
With tensions rising on the South Coast over migrant arrivals the charity put out a statement, which said: "Given the unacceptable abuse our people have faced, and with protest activity taking place at RNLI locations, we have taken action to help ensure the safety and well-being of our volunteers and staff.
"As well as enhancing security at RNLI locations, we issued guidance to our people earlier this week on how to keep themselves safe."
The statement added: "This guidance included how to manage potentially challenging interactions with members of the public, and where appropriate, choosing not to wear RNLI branded clothing.
"Our people have been reminded that their safety comes first, and they are encouraged to report relevant incidents internally and, where appropriate, to the police."
Vikki Slade, the Liberal Democrat MP for Mid Dorset and North Poole, where the RNLI is headquartered, described the situation as "absolutely shameful".
She told Sky News' Mark Austin that the abuse that RNLI volunteers had been faced with was "beyond belief" and called on the government to make it "really clear that the RNLI are [only] there to rescue and hand to the authorities".
On Wednesday, the RNLI said it was working "to understand the decision to deny access" to the boat carrying the migrants.
It added it was "disappointed with the nature of the communication" with its crew who "voluntarily give their time to save the lives of others at sea".
Read more:
PE teacher had sex with pupil
Two arrested for 'assisting Iran'
When the migrants were landed at Eastney in Portsmouth, anti-migrant protesters blocked road access to the port.
Police officers were injured and vehicles were damaged during the protest.
On Thursday, it was announced police chiefs have stepped up planning and intelligence-gathering ahead of the weekend after Home Secretary Shabana Mahmood warned anti-migration protesters are trying to intimidate communities.
Ms Mahmood said stronger police action was needed to deal with new tactics used by groups such as Patriot Platform earlier this week, after crowds also blocked road access to the Port of Dover on Saturday.
No arrests have been made in connection with either of the weekend's incidents.
But it is understood the government believes protesters wearing face coverings at the demonstration in Dover could have been arrested.
Ms Mahmood also made it clear she expects police to make full use of their powers to stop protesters wearing face coverings.
A group called "Portsmouth patriots" plans to march in the city on Saturday, where a counter-demonstration is also planned.
Ms Mahmood told police chiefs: "These scenes have caused disruption for people and, given that people are dressed in black wearing balaclavas, there is a fear factor and obvious malign intent being communicated to our residents.
"This makes it different from other protests, so we need to make sure we are learning lessons."
(c) Sky News 2026: RNLI warns staff not to wear uniform after they suffer 'unacceptable abuse'
Two arrested in London on suspicion of assisting Iran's intelligence service
Seven men arrested after four were stabbed during fight in Bromley
Ex-employees based in the UK sue GTA VI developer Rockstar for unfair dismissal
Former PE teacher guilty of sexual activity with 16-year-old schoolboy
British man 'prepared to sabotage UK drone factory for Russia', court hears