By Jussi Rosendahl and Shadia Nasralla HELSINKI/VIENNA (Reuters) - European policymakers saw Greek Prime Minister Alexis Tsipras' resignation and election call as a gambit to consolidate support for Athens' new bailout, but the move unnerved some investors who worried on Friday that reforms could be delayed. Tsipras resigned on Thursday, hoping to strengthen his hold on power in snap elections after seven months in office in which he fought Greece's creditors for a better bailout deal but had to cave in. Thomas Wieser, the head of the Euro Working Group which prepares decisions for meetings of euro zone finance ministers, took a sanguine view of the move.