RWE chief operating officer Paul Coffey said: "We are not in a place to see large-scale deployment of offshore wind. It would be very difficult to move ahead with the terms on the table.
"We can't invest on promises and a lack of clarity, and we are running out of time for offshore wind."
There has been a growing political row in the UK about energy, both between the main political parties and within government.
In September the opposition Labour Party promised to freeze energy prices for two years if it wins power.
Over the last couple of weeks, two of the UK’s biggest energy companies, SSE and British Gas, announced price increases of 8.2% and 9.2% respectively.
After announcing the price increase, SSE’s chief executive, Alistair Phillips-Davies, said the utility would stop investment in offshore wind and new power plants until the 2015 election because of political uncertainty around energy.
There have also been tensions within the coalition government with the Liberal Democrats, who are generally supportive of wind energy, battling with their Conservative Party colleagues.
Coffey said: "The next six months are critical, but politicians are treating the issue as a political football to beat up the utility companies."
RWE Innogy and SSE are the developers behind the 500MW Galloper wind project off England’s Essex coast.
Coffey said: "I have to be absolutely clear when I invest another £1 billion (EUR 1.2 billion) that we will not come unstuck. At the moment, I can't tell you if Galloper will work or not."
This is not the first time energy companies have raised their concerns about the UK government’s energy policies and threatened to pull out of plans to build wind projects.
In October last year offshore wind turbine manufacturers wrote to UK energy minister Ed Davey expressing concern at the country's energy policy.
Siemens, Vestas, Alstom, Areva, Mitsubishi, Doosan, Gamesa and Vestas signed a letter asking Davey to push forward binding 2030 targets. The companies said the policy would reduce the risks in investing in the UK.
The letter also made threats to cancel plans to build turbine manufacturing plants in the UK.
It said: "Historically the UK has benefited from being known as a country with low political risk for energy investments. Undermining that reputation would have damaging consequences for the scale of future investments in the UK energy sector. It is important to protect that reputation carefully."
The manufacturers expressed concern at the lack of clarity in the UK's energy policy, especially with regard to the investment required for the 33GW Round 3 offshore programme.
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