LONDON (Reuters) - Britain and Germany agreed on Sunday they remained committed to the nuclear deal with Iran after a U.S. decision to decertify the agreement, a spokeswoman said after a call between Prime Minister Theresa May and German Chancellor Angela Merkel.  They agreed the UK and Germany both remained firmly committed to the deal,  the spokeswoman said in a statement.  They also agreed the international community needed to continue to come together to push back against Iran s destabilizing regional activity, and to explore ways of addressing concerns about Iran s ballistic missile program.   