[Raynor]

No, all referrences I know state that they were only forbidden to show their full power in their "contest of the growth of the Shadow":

Originally Posted by The Istari, Part Four, Unfinished Tales

And this the Valar did, desiring to amend the errors of old, especially that they had attempted to guard and seclude the Eldar by their own might and glory fully revealed; whereas now their emissaries were forbidden to reveal themselves in forms of majesty, or to seek to rule the wills of Men and Elves by open display of power, but coming in shapes weak and humble were bidden to advise and persuade Men and Elves to good, and to seek to unite in love and understanding all those whom Sauron, should he come again, would endeavour to dominate and corrupt.

Originally Posted by Tale of Years, Appendix B, LotR

It was afterwards said that they came out of the Far West and were messengers sent to contest the power of Sauron, and to unite all those who had the will to resist him; but they were forbidden to match his power with power, or to seek to dominate Elves or Men by force and fear.

Originally Posted by Letter #156

At this point in the fabulous history the purpose was precisely to limit and hinder their exhibition of 'power' on the physical plane, and so that they should do what they were primarily sent for: train, advise, instruct, arouse the hearts and minds of those threatened by Sauron to a resistance with their own strengths; and not just to do the job for them.