Currently, 16 offshore wind farms are under construction in Europe, which upon completion will bring online 4.9GW of power capacity.
According to the report, 224 turbines, with a total capacity of 781MW, were connected to the grid in the first half of 2014, 25% less than during the same period in 2013, where new links accounted for 1,045MW.
Additionally, about 310 turbines are due for grid connection, which when linked will add a further 1,200MW of offshore wind capacity.
EWEA deputy chief executive officer Justin Wilkes said despite offshore wind power installations being lower than in the first six months of 2013, it remains the fastest growing power sector in Europe.
"To ensure healthy growth in the latter part of the decade, and to ensure offshore wind energy plays its role in meeting the EU’s competitiveness, security, renewable and climate objectives, the industry must be given longer-term visibility," Wilkes added.
"An ambitious deal on the 2030 Climate and Energy package by the EU’s Heads of State in October would send the right signal, making their decision particularly important for the offshore wind sector."
