A group of about 20 caravans moved on to the recreation ground at Muscliffe last week and the council is taking legal steps to remove them.
MP Tobias Ellwood, councillors and residents called on police to "act immediately".
Dorset Police said it would only move travellers on in "exceptional circumstances".
Bournemouth Borough Council said it had no traveller sites and there were no pitches available for travellers in the borough.
Mr Ellwood, MP for Bournemouth East, said police had powers to go in "firm and fast" and "if there's six or more pitches, then they have the right, straight away, to tell these individuals to move on".
Supt Mike Rogers said: "We will only move travellers on in absolute exceptional circumstances, in a last case scenario.
"The basic situation would be one where the community... are denied, in entirety, the facilities of a particular area or a particular piece of land.
"In this situation, this has not occurred."
On Friday, Bournemouth Borough Council said it was aware of the unauthorised encampment and the site was being visited and monitored daily.
On Monday it announced it had started legal proceedings to repossess the land.
Bournemouth and other councils across Dorset began a consultation in 2011 to identify potential sites to accommodate Gypsies and travellers.
The plan, required by government, will allocate permanent and transit sites for the next 15 years, is due to be adopted by the end of this year.
A 2013 report found, while there was a need for 88 pitches across Bournemouth, Poole and Dorset, the total supply was eight.
Bournemouth Borough Council leader John Beesley said: "The council's position remains the same as it has done for the past three years.
"We do not believe that there are any suitable sites for a permanent transit facility within the Bournemouth boundary."

Joachim Low's world champions went ahead through Mario Gomez's penalty after 13 minutes.
But Slovakia, who are in the same group as England and Wales in France, hit back through Marek Hamsik, Michal Duris and Juraj Kucka in Augsburg.
The game was played in heavy rain with concerns the match might be abandoned.
Germany, who are in the same group as Northern Ireland at Euro 2016, have to finalise their 23-man squad by midnight on Tuesday.
Elsewhere, Euro 2012 winners Spain continued their preparations for the defence of their title with a 3-1 win against Bosnia-Herzegovina in Switzerland.
Celta Vigo forward Nolito scored the opening two goals for Vicente del Bosque's side.
Chelsea midfielder Pedro added a late third after Emir Spahic, who was later sent off, had reduced the deficit for Bosnia.
Spain gave a debut at right-back for Arsenal's Hector Bellerin.
Southampton's Graziano Pelle scored the only goal as Italy beat Scotland 1-0 in Malta, while Portugal - who meet England at Wembley on Thursday - were 3-0 winners at home to Norway.

The Manchester United forward, 30, scored seven goals in their Euro 2016 qualifying campaign, but has not played since a knee injury in February.
The top two scorers in this season's Premier League are both England strikers, Harry Kane and Jamie Vardy.
"Over the past two years my form for England has been really good. I've scored a lot of goals," Rooney said.
"I'll keep trying to, first and foremost, help the team be successful and if I can score the goals to help achieve that then that'll be great.
"I've still got a few years left, I feel," he told the PFA's 4 The Player magazine. "I'm always just thinking about what comes next and making sure I'm at my best for the summer.
"I feel I'm a lot more patient now in my play. When I was younger I could be impatient and I'd end up in positions I didn't really need to be in."
Police say they have no power to remove an illegal encampment in Bournemouth, despite calls for them to act.
[NEXT_CONCEPT]
Germany suffered a third defeat in four games as they were beaten 3-1 by Slovakia in the final match before their Euro 2016 squad is finalised.
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England captain and record goalscorer Wayne Rooney is confident he has "a few years left" at international level.