In an interview with The HuffingtonPost UK, ambassador Witold Sobkow said Warsaw was willing to "accommodate" some British demands.
Asked if Poland would be willing to allow Cameron to substantially change Britain’s relationship with Brussels ahead of a in/out referendum, he said: "Yes. We see a lot of room for manoeuvre."
"We all want a better functioning EU, respecting subsidiarity, and reducing its bureaucratic burden."
However despite Poland's willingness to listen to the UK, Sobkow warned the opposition of other member states may get in the way.
"Some changes will be easier - they will not imply treaty changes. Others may be more difficult, as any treaty changes may lead to ratifications in all the EU member states.
"There is no appetite for such far reaching changes now, but, who knows, in 2-3 years," he said. "The EU is changing, as we can see, for example, in the case of new banking supervision arrangements."
"I believe we can accommodate some British proposals. We would definitely want Britain to remain a member."
The ambassador’s comments will be seen as a boost for Cameron, who has faced sharp criticism from other European politicians who have been highly critical of his approach.
On Wednesday, German foreign minister Guido Westerwelle told the Financial Times that there could be no "cherry picking" of EU rules.
"The current European settlement may not be to everybody’s liking in every respect, but that is the nature of every good compromise," he said.
"One thing, however, holds true for all of us: there are no rights without duties. There can be no cherry-picking. Saying ‘You either do what I want or I’ll leave!’ is not an attitude that works, either in personal relationships or in a community of nations."
Ambassador Sobkow, who has previously served as Poland's UN ambassador, told HuffPost UK that while it British voters had the "unquestionable" right to leave the EU if they wanted, it would be "bad for Poland and the EU".
"Britain is our close, valuable partner in the EU. We think it provides the right balance in the EU," he said.
He added: "We like and respect the UK, home for thousands of Poles who contribute to the UK's prosperity and enhance the UK's competitiveness."
The Polish foreign minister recently caused a stir when he said the UK was now a "country under care" given the possibility it may leave the EU. Sobkow said this was a warning to other member states not to let Britain leave.
Poland has traditionally been seen as one of the UK’s closest allies within the union. However in recent years the two nation’s paths have diverged. While Britain is looking to detach itself from the core, Poland is keen to pursue deeper integration.
Sobkow said rather than creating looser ties between EU member states, Poland wanted to create a global "superpower".
"We want the EU to be a strong global player with whom everyone recons with," he said.
Sobkow said that if the UK left the EU it would mean "fundamental changes" in the union as no country has ever left.
"The UK, to some extent, created the single market. It has special relationships with the USA, supports transatlantic relations, and is able to influence politics globally. It has a huge influence in the world through its links with the Commonwealth countries,” he said.
"Leaving the EU would mean not only less power for the UK, but also for the EU. It would harm our global interests," he added.
Related on HuffPost: