A reported published by the US-based Critical Threats Project (CTP) said only seven protests were recorded across six provinces on Tuesday, a sharp drop from last Thursday, when 156 demonstrations were documented in 27 of Iran's 31 provinces.
The CTP is run by the US-based Institute for the Study of War and American Enterprise Institute.
The authors cautioned that the true scale of protest activity remains difficult to assess due to widespread internet shutdowns that have restricted the flow of information out of the country.
They also pointed to the high number of reported casualties during the unrest, noting that "the level of brutality may be discouraging protesters and decreasing the rate of protest activity."
Two European officials said US military intervention appeared likely, with one saying it could come in the next 24 hours.
An Israeli official also said it appeared Trump had taken a decision to intervene although the scope and timing had yet to be made clear.
A US official, speaking on condition of anonymity, said the United States was withdrawing some personnel from key bases in the region as a precaution given heightened regional tensions.
Two European officials said US military intervention appeared likely, with one saying it could come in the next 24 hours.
An Israeli official also said it appeared Trump had taken a decision to intervene, although the scope and timing had yet to be made clear.
Qatar said drawdowns from its al-Udeid air base, the biggest US base in the region, were "being undertaken in response to the current regional tensions".
Three diplomats said some personnel had been told to leave the base although there were no immediate signs of large numbers of troops being bussed out to a football stadium and shopping mall as took place hours before an Iranian missile strike last year.
The US-based Human Rights Activists News Agency (HRANA) has said more than 2400 demonstrators have been killed, a figure that would make the crackdown the deadliest in Iran's recent history.
The toll could not be independently confirmed.
Residents of Tehran said on Wednesday that there was tense calm in the capital.
Police and security forces remain stationed at many key locations but their presence is less extensive than over the weekend, residents said.
Iranian authorities continue to move against protest organisers.
State media reported on Wednesday that security forces had arrested several alleged protest leaders in the western province of Chaharmahal and Bakhtiari.
According to state radio, the intelligence arm of the Islamic Revolutionary Guard Corps detained what it described as "key figures responsible for insecurity".
The province was the scene of some of the fiercest clashes at the start of the protest movement in late December.
After security forces opened fire on demonstrators, severe unrest erupted in the city of Lordegan, resulting in numerous deaths.
Chaharmahal and Bakhtiari is an economically underdeveloped region where distrust of the state runs high, and analysts say the harsh security response contributed to the rapid escalation there.
The judiciary also warned the public against co-operating with Iran International, a London-based Persian-language broadcaster that authorities accuse of spreading disinformation on behalf of Saudi Arabia.
Any co-operation or exchange of information with the channel is prohibited, the Prosecutor General's Office said, according to state media.
Iran has designated the company behind the broadcaster a terrorist organisation.
Protests began in Tehran on December 28 as demonstrations by shopkeepers over a sharp fall in the value of the Iranian rial and worsening economic conditions, before evolving into a country-wide uprising against the country's rulers.
with Reuters and AP
